CLEANUP: makefile: properly indent ifeq/ifneq conditional blocks

Some conditional blocks have become out of control over time and are
totally unreadble. It took 15 minutes to figure what "endif" matched
what "if" in the PCRE one for example, and DA and 51D use multiple
levels as well that are not easy to sort out.

Let's reindent the whole thing. Most places that were already indented
used 2 spaces per level, so here we're keeping that principle. It was
just not done on the two last ones that are used to define some rules
because we don't want spaces before rule names. A few had the opening
condition indicated on the endif line.

It would be desirable that over time this more maintainable layout is
preserved.
diff --git a/Makefile b/Makefile
index 808a112..5213c6f 100644
--- a/Makefile
+++ b/Makefile
@@ -200,7 +200,7 @@
 SPEC_CFLAGS += $(call cc-nowarn,atomic-alignment)
 
 ifneq ($(ERR),)
-SPEC_CFLAGS += -Werror
+  SPEC_CFLAGS += -Werror
 endif
 
 #### Memory usage tuning
@@ -321,7 +321,7 @@
 # SLZ is always supported unless explicitly disabled by passing USE_SLZ=""
 # or disabled by enabling ZLIB using USE_ZLIB=1
 ifeq ($(USE_ZLIB),)
-USE_SLZ    = default
+  USE_SLZ    = default
 endif
 
 # generic system target has nothing specific
@@ -458,9 +458,9 @@
 # linking with it by default as it's not always available nor deployed
 # (especially on archs which do not need it).
 ifneq ($(USE_THREAD),)
-ifneq ($(shell $(CC) $(CFLAGS) -dM -E -xc - </dev/null 2>/dev/null | grep -c 'LOCK_FREE.*1'),0)
-  USE_LIBATOMIC   = implicit
-endif
+  ifneq ($(shell $(CC) $(CFLAGS) -dM -E -xc - </dev/null 2>/dev/null | grep -c 'LOCK_FREE.*1'),0)
+    USE_LIBATOMIC   = implicit
+  endif
 endif
 
 #### Determine version, sub-version and release date.
@@ -469,23 +469,23 @@
 # holding the same names in the current directory.
 
 ifeq ($(IGNOREGIT),)
-VERSION := $(shell [ -d .git/. ] && (git describe --tags --match 'v*' --abbrev=0 | cut -c 2-) 2>/dev/null)
-ifneq ($(VERSION),)
-# OK git is there and works.
-SUBVERS := $(shell comms=`git log --format=oneline --no-merges v$(VERSION).. 2>/dev/null | wc -l | tr -d '[:space:]'`; commit=`(git log -1 --pretty=%h --abbrev=6) 2>/dev/null`; [ $$comms -gt 0 ] && echo "-$$commit-$$comms")
-VERDATE := $(shell git log -1 --pretty=format:%ci | cut -f1 -d' ' | tr '-' '/')
-endif
+  VERSION := $(shell [ -d .git/. ] && (git describe --tags --match 'v*' --abbrev=0 | cut -c 2-) 2>/dev/null)
+  ifneq ($(VERSION),)
+    # OK git is there and works.
+    SUBVERS := $(shell comms=`git log --format=oneline --no-merges v$(VERSION).. 2>/dev/null | wc -l | tr -d '[:space:]'`; commit=`(git log -1 --pretty=%h --abbrev=6) 2>/dev/null`; [ $$comms -gt 0 ] && echo "-$$commit-$$comms")
+    VERDATE := $(shell git log -1 --pretty=format:%ci | cut -f1 -d' ' | tr '-' '/')
+  endif
 endif
 
 # Last commit version not found, take it from the files.
 ifeq ($(VERSION),)
-VERSION := $(shell cat VERSION 2>/dev/null || touch VERSION)
+  VERSION := $(shell cat VERSION 2>/dev/null || touch VERSION)
 endif
 ifeq ($(SUBVERS),)
-SUBVERS := $(shell (grep -v '\$$Format' SUBVERS 2>/dev/null || touch SUBVERS) | head -n 1)
+  SUBVERS := $(shell (grep -v '\$$Format' SUBVERS 2>/dev/null || touch SUBVERS) | head -n 1)
 endif
 ifeq ($(VERDATE),)
-VERDATE := $(shell (grep -v '^\$$Format' VERDATE 2>/dev/null || touch VERDATE) | head -n 1 | cut -f1 -d' ' | tr '-' '/')
+  VERDATE := $(shell (grep -v '^\$$Format' VERDATE 2>/dev/null || touch VERDATE) | head -n 1 | cut -f1 -d' ' | tr '-' '/')
 endif
 
 # this one is always empty by default and appended verbatim
@@ -510,79 +510,79 @@
 OPTIONS_CFLAGS += $(call opts_as_defines)
 
 ifneq ($(USE_LIBCRYPT),)
-ifneq ($(TARGET),openbsd)
-ifneq ($(TARGET),osx)
-OPTIONS_LDFLAGS += -lcrypt
-endif
-endif
+  ifneq ($(TARGET),openbsd)
+    ifneq ($(TARGET),osx)
+      OPTIONS_LDFLAGS += -lcrypt
+    endif
+  endif
 endif
 
 ifneq ($(USE_ZLIB),)
-# Use ZLIB_INC and ZLIB_LIB to force path to zlib.h and libz.{a,so} if needed.
-OPTIONS_CFLAGS  += $(if $(ZLIB_INC),-I$(ZLIB_INC))
-OPTIONS_LDFLAGS += $(if $(ZLIB_LIB),-L$(ZLIB_LIB)) -lz
+  # Use ZLIB_INC and ZLIB_LIB to force path to zlib.h and libz.{a,so} if needed.
+  OPTIONS_CFLAGS  += $(if $(ZLIB_INC),-I$(ZLIB_INC))
+  OPTIONS_LDFLAGS += $(if $(ZLIB_LIB),-L$(ZLIB_LIB)) -lz
 endif
 
 ifneq ($(USE_SLZ),)
-OPTIONS_OBJS   += src/slz.o
+  OPTIONS_OBJS   += src/slz.o
 endif
 
 ifneq ($(USE_POLL),)
-OPTIONS_OBJS   += src/ev_poll.o
+  OPTIONS_OBJS   += src/ev_poll.o
 endif
 
 ifneq ($(USE_EPOLL),)
-OPTIONS_OBJS   += src/ev_epoll.o
+  OPTIONS_OBJS   += src/ev_epoll.o
 endif
 
 ifneq ($(USE_KQUEUE),)
-OPTIONS_OBJS   += src/ev_kqueue.o
+  OPTIONS_OBJS   += src/ev_kqueue.o
 endif
 
 ifneq ($(USE_EVPORTS),)
-OPTIONS_OBJS   += src/ev_evports.o
+  OPTIONS_OBJS   += src/ev_evports.o
 endif
 
 ifneq ($(USE_RT),)
-OPTIONS_LDFLAGS += -lrt
+  OPTIONS_LDFLAGS += -lrt
 endif
 
 ifneq ($(USE_THREAD),)
-OPTIONS_LDFLAGS += -lpthread
+  OPTIONS_LDFLAGS += -lpthread
 endif
 
 ifneq ($(USE_BACKTRACE),)
-OPTIONS_LDFLAGS += -Wl,$(if $(EXPORT_SYMBOL),$(EXPORT_SYMBOL),--export-dynamic)
+  OPTIONS_LDFLAGS += -Wl,$(if $(EXPORT_SYMBOL),$(EXPORT_SYMBOL),--export-dynamic)
 endif
 
 ifneq ($(USE_CPU_AFFINITY),)
-OPTIONS_OBJS   += src/cpuset.o
+  OPTIONS_OBJS   += src/cpuset.o
 endif
 
 ifneq ($(USE_OPENSSL),)
-# OpenSSL is packaged in various forms and with various dependencies.
-# In general -lssl is enough, but on some platforms, -lcrypto may be needed,
-# reason why it's added by default. Some even need -lz, then you'll need to
-# pass it in the "ADDLIB" variable if needed. If your SSL libraries are not
-# in the usual path, use SSL_INC=/path/to/inc and SSL_LIB=/path/to/lib.
-ifeq ($(USE_OPENSSL_WOLFSSL),)
-OPTIONS_CFLAGS  += $(if $(SSL_INC),-I$(SSL_INC))
-OPTIONS_LDFLAGS += $(if $(SSL_LIB),-L$(SSL_LIB)) -lssl -lcrypto
-endif
-OPTIONS_OBJS  += src/ssl_sock.o src/ssl_ckch.o src/ssl_sample.o src/ssl_crtlist.o src/cfgparse-ssl.o src/ssl_utils.o src/jwt.o src/ssl_ocsp.o
+  # OpenSSL is packaged in various forms and with various dependencies.
+  # In general -lssl is enough, but on some platforms, -lcrypto may be needed,
+  # reason why it's added by default. Some even need -lz, then you'll need to
+  # pass it in the "ADDLIB" variable if needed. If your SSL libraries are not
+  # in the usual path, use SSL_INC=/path/to/inc and SSL_LIB=/path/to/lib.
+  ifeq ($(USE_OPENSSL_WOLFSSL),)
+    OPTIONS_CFLAGS  += $(if $(SSL_INC),-I$(SSL_INC))
+    OPTIONS_LDFLAGS += $(if $(SSL_LIB),-L$(SSL_LIB)) -lssl -lcrypto
+  endif
+  OPTIONS_OBJS  += src/ssl_sock.o src/ssl_ckch.o src/ssl_sample.o src/ssl_crtlist.o src/cfgparse-ssl.o src/ssl_utils.o src/jwt.o src/ssl_ocsp.o
 endif
 
 ifneq ($(USE_OPENSSL_WOLFSSL),)
-OPTIONS_CFLAGS   += $(if $(WOLFSSL_INC),-I$(WOLFSSL_INC) -I$(WOLFSSL_INC)/wolfssl)
-OPTIONS_LDFLAGS  += $(if $(WOLFSSL_LIB),-L$(WOLFSSL_LIB)) -lwolfssl
+  OPTIONS_CFLAGS   += $(if $(WOLFSSL_INC),-I$(WOLFSSL_INC) -I$(WOLFSSL_INC)/wolfssl)
+  OPTIONS_LDFLAGS  += $(if $(WOLFSSL_LIB),-L$(WOLFSSL_LIB)) -lwolfssl
 endif
 
 ifneq ($(USE_ENGINE),)
-# OpenSSL 3.0 emits loud deprecation warnings by default when building with
-# engine support, and this option is made to silence them. Better use it
-# only when absolutely necessary, until there's a viable alternative to the
-# engine API.
-OPTIONS_CFLAGS += -DOPENSSL_SUPPRESS_DEPRECATED
+  # OpenSSL 3.0 emits loud deprecation warnings by default when building with
+  # engine support, and this option is made to silence them. Better use it
+  # only when absolutely necessary, until there's a viable alternative to the
+  # engine API.
+  OPTIONS_CFLAGS += -DOPENSSL_SUPPRESS_DEPRECATED
 endif
 
 ifneq ($(USE_QUIC),)
@@ -597,211 +597,209 @@
 endif
 
 ifneq ($(USE_LUA),)
-check_lua_inc = $(shell if [ -d $(2)$(1) ]; then echo $(2)$(1); fi;)
-LUA_INC      := $(firstword $(foreach lib,lua5.4 lua54 lua5.3 lua53 lua,$(call check_lua_inc,$(lib),"/usr/include/")))
-OPTIONS_CFLAGS  += $(if $(LUA_INC),-I$(LUA_INC))
+  check_lua_inc = $(shell if [ -d $(2)$(1) ]; then echo $(2)$(1); fi;)
+  LUA_INC      := $(firstword $(foreach lib,lua5.4 lua54 lua5.3 lua53 lua,$(call check_lua_inc,$(lib),"/usr/include/")))
+  OPTIONS_CFLAGS  += $(if $(LUA_INC),-I$(LUA_INC))
 
-check_lua_lib = $(shell echo "int main(){}" | $(CC) -o /dev/null -x c - $(2) -l$(1) 2>/dev/null && echo $(1))
-LUA_LIB       =
-LUA_LD_FLAGS := -Wl,$(if $(EXPORT_SYMBOL),$(EXPORT_SYMBOL),--export-dynamic) $(if $(LUA_LIB),-L$(LUA_LIB))
+  check_lua_lib = $(shell echo "int main(){}" | $(CC) -o /dev/null -x c - $(2) -l$(1) 2>/dev/null && echo $(1))
+  LUA_LIB       =
+  LUA_LD_FLAGS := -Wl,$(if $(EXPORT_SYMBOL),$(EXPORT_SYMBOL),--export-dynamic) $(if $(LUA_LIB),-L$(LUA_LIB))
 
-# Try to automatically detect the Lua library if not set
-ifeq ($(LUA_LIB_NAME),)
-LUA_LIB_NAME := $(firstword $(foreach lib,lua5.4 lua54 lua5.3 lua53 lua,$(call check_lua_lib,$(lib),$(LUA_LD_FLAGS))))
-endif
+  # Try to automatically detect the Lua library if not set
+  ifeq ($(LUA_LIB_NAME),)
+    LUA_LIB_NAME := $(firstword $(foreach lib,lua5.4 lua54 lua5.3 lua53 lua,$(call check_lua_lib,$(lib),$(LUA_LD_FLAGS))))
+  endif
 
-# Lua lib name must be set now (forced/detected above)
-ifeq ($(LUA_LIB_NAME),)
-$(error unable to automatically detect the Lua library name, you can enforce its name with LUA_LIB_NAME=<name> (where <name> can be lua5.4, lua54, lua, ...))
-endif
+  # Lua lib name must be set now (forced/detected above)
+  ifeq ($(LUA_LIB_NAME),)
+    $(error unable to automatically detect the Lua library name, you can enforce its name with LUA_LIB_NAME=<name> (where <name> can be lua5.4, lua54, lua, ...))
+  endif
 
-ifneq ($(HLUA_PREPEND_PATH),)
-OPTIONS_CFLAGS  += -DHLUA_PREPEND_PATH=$(HLUA_PREPEND_PATH)
-BUILD_OPTIONS += HLUA_PREPEND_PATH=$(HLUA_PREPEND_PATH)
-endif # HLUA_PREPEND_PATH
+  ifneq ($(HLUA_PREPEND_PATH),)
+    OPTIONS_CFLAGS  += -DHLUA_PREPEND_PATH=$(HLUA_PREPEND_PATH)
+    BUILD_OPTIONS   += HLUA_PREPEND_PATH=$(HLUA_PREPEND_PATH)
+  endif # HLUA_PREPEND_PATH
 
-ifneq ($(HLUA_PREPEND_CPATH),)
-OPTIONS_CFLAGS  += -DHLUA_PREPEND_CPATH=$(HLUA_PREPEND_CPATH)
-BUILD_OPTIONS += HLUA_PREPEND_CPATH=$(HLUA_PREPEND_CPATH)
-endif # HLUA_PREPEND_CPATH
+  ifneq ($(HLUA_PREPEND_CPATH),)
+    OPTIONS_CFLAGS  += -DHLUA_PREPEND_CPATH=$(HLUA_PREPEND_CPATH)
+    BUILD_OPTIONS   += HLUA_PREPEND_CPATH=$(HLUA_PREPEND_CPATH)
+  endif # HLUA_PREPEND_CPATH
 
-USE_MATH         = implicit
-OPTIONS_LDFLAGS += $(LUA_LD_FLAGS) -l$(LUA_LIB_NAME)
-OPTIONS_OBJS    += src/hlua.o src/hlua_fcn.o
+  USE_MATH         = implicit
+  OPTIONS_LDFLAGS += $(LUA_LD_FLAGS) -l$(LUA_LIB_NAME)
+  OPTIONS_OBJS    += src/hlua.o src/hlua_fcn.o
 endif # USE_LUA
 
 ifneq ($(USE_PROMEX),)
-OPTIONS_OBJS    += addons/promex/service-prometheus.o
+  OPTIONS_OBJS    += addons/promex/service-prometheus.o
 endif
 
 ifneq ($(USE_DEVICEATLAS),)
-# Use DEVICEATLAS_SRC and possibly DEVICEATLAS_INC and DEVICEATLAS_LIB to force path
-# to DeviceAtlas headers and libraries if needed.
-DEVICEATLAS_INC = $(DEVICEATLAS_SRC)
-DEVICEATLAS_LIB = $(DEVICEATLAS_SRC)
-ifeq ($(DEVICEATLAS_SRC),)
-OPTIONS_LDFLAGS += -lda
-else
-ifeq ($(USE_PCRE),)
-ifeq ($(USE_PCRE2),)
-$(error the DeviceAtlas module needs the PCRE or the PCRE2 library in order to compile)
-endif
-endif
-ifneq ($(USE_PCRE2),)
-OPTIONS_CFLAGS  += -DDA_REGEX_HDR=\"dac_pcre2.c\" -DDA_REGEX_TAG=2
-endif
-OPTIONS_OBJS	+= $(DEVICEATLAS_LIB)/Os/daunix.o
-OPTIONS_OBJS	+= $(DEVICEATLAS_LIB)/dadwcom.o
-OPTIONS_OBJS	+= $(DEVICEATLAS_LIB)/dasch.o
-OPTIONS_OBJS	+= $(DEVICEATLAS_LIB)/json.o
-OPTIONS_OBJS	+= $(DEVICEATLAS_LIB)/dac.o
-endif
-OPTIONS_OBJS	+= addons/deviceatlas/da.o
-OPTIONS_CFLAGS += $(if $(DEVICEATLAS_INC),-I$(DEVICEATLAS_INC))
+  # Use DEVICEATLAS_SRC and possibly DEVICEATLAS_INC and DEVICEATLAS_LIB to force path
+  # to DeviceAtlas headers and libraries if needed.
+  DEVICEATLAS_INC = $(DEVICEATLAS_SRC)
+  DEVICEATLAS_LIB = $(DEVICEATLAS_SRC)
+  ifeq ($(DEVICEATLAS_SRC),)
+    OPTIONS_LDFLAGS += -lda
+  else
+    ifeq ($(USE_PCRE),)
+      ifeq ($(USE_PCRE2),)
+        $(error the DeviceAtlas module needs the PCRE or the PCRE2 library in order to compile)
+      endif
+    endif
+    ifneq ($(USE_PCRE2),)
+      OPTIONS_CFLAGS  += -DDA_REGEX_HDR=\"dac_pcre2.c\" -DDA_REGEX_TAG=2
+    endif
+    OPTIONS_OBJS += $(DEVICEATLAS_LIB)/Os/daunix.o
+    OPTIONS_OBJS += $(DEVICEATLAS_LIB)/dadwcom.o
+    OPTIONS_OBJS += $(DEVICEATLAS_LIB)/dasch.o
+    OPTIONS_OBJS += $(DEVICEATLAS_LIB)/json.o
+    OPTIONS_OBJS += $(DEVICEATLAS_LIB)/dac.o
+  endif
+  OPTIONS_OBJS += addons/deviceatlas/da.o
+  OPTIONS_CFLAGS += $(if $(DEVICEATLAS_INC),-I$(DEVICEATLAS_INC))
 endif
 
 ifneq ($(USE_51DEGREES),)
-ifneq ($(USE_51DEGREES_V4),)
-$(error cannot compile both 51Degrees V3 and V4 engine support)
-endif
+  ifneq ($(USE_51DEGREES_V4),)
+    $(error cannot compile both 51Degrees V3 and V4 engine support)
+  endif
 endif
 
 ifneq ($(USE_51DEGREES)$(USE_51DEGREES_V4),)
-# Use 51DEGREES_SRC and possibly 51DEGREES_INC and 51DEGREES_LIB to force path
-# to 51degrees headers and libraries if needed.
-51DEGREES_INC = $(51DEGREES_SRC)
-51DEGREES_LIB = $(51DEGREES_SRC)
-ifneq ($(USE_51DEGREES_V4),)
-_51DEGREES_SRC   = $(shell find $(51DEGREES_LIB) -maxdepth 2 -name '*.c')
-OPTIONS_OBJS    += $(_51DEGREES_SRC:%.c=%.o)
-else
-OPTIONS_OBJS    += $(51DEGREES_LIB)/../cityhash/city.o
-OPTIONS_OBJS    += $(51DEGREES_LIB)/51Degrees.o
-endif
-OPTIONS_OBJS    += addons/51degrees/51d.o
-OPTIONS_CFLAGS  += $(if $(51DEGREES_INC),-I$(51DEGREES_INC))
-ifneq ($(USE_51DEGREES_V4),)
-OPTIONS_CFLAGS  += -DUSE_51DEGREES_V4
-endif
-ifeq ($(USE_THREAD),)
-OPTIONS_CFLAGS  += -DFIFTYONEDEGREES_NO_THREADING
-ifneq ($(USE_51DEGREES_V4),)
-OPTIONS_CFLAGS  += -DFIFTYONE_DEGREES_NO_THREADING
-endif
-else
-ifeq ($(USE_51DEGREES_V4),)
-OPTIONS_OBJS    += $(51DEGREES_LIB)/../threading.o
-endif
-endif
+  # Use 51DEGREES_SRC and possibly 51DEGREES_INC and 51DEGREES_LIB to force path
+  # to 51degrees headers and libraries if needed.
+  51DEGREES_INC = $(51DEGREES_SRC)
+  51DEGREES_LIB = $(51DEGREES_SRC)
+  ifneq ($(USE_51DEGREES_V4),)
+    _51DEGREES_SRC   = $(shell find $(51DEGREES_LIB) -maxdepth 2 -name '*.c')
+    OPTIONS_OBJS    += $(_51DEGREES_SRC:%.c=%.o)
+  else
+    OPTIONS_OBJS    += $(51DEGREES_LIB)/../cityhash/city.o
+    OPTIONS_OBJS    += $(51DEGREES_LIB)/51Degrees.o
+  endif
+  OPTIONS_OBJS    += addons/51degrees/51d.o
+  OPTIONS_CFLAGS  += $(if $(51DEGREES_INC),-I$(51DEGREES_INC))
+  ifneq ($(USE_51DEGREES_V4),)
+    OPTIONS_CFLAGS  += -DUSE_51DEGREES_V4
+  endif
+  ifeq ($(USE_THREAD),)
+    OPTIONS_CFLAGS  += -DFIFTYONEDEGREES_NO_THREADING
+    ifneq ($(USE_51DEGREES_V4),)
+      OPTIONS_CFLAGS  += -DFIFTYONE_DEGREES_NO_THREADING
+    endif
+    else
+      ifeq ($(USE_51DEGREES_V4),)
+      OPTIONS_OBJS    += $(51DEGREES_LIB)/../threading.o
+    endif
+  endif
 
-OPTIONS_LDFLAGS += $(if $(51DEGREES_LIB),-L$(51DEGREES_LIB))
-USE_MATH         = implicit
-ifneq ($(USE_51DEGREES_V4),)
-USE_LIBATOMIC    = implicit
-endif
+  OPTIONS_LDFLAGS += $(if $(51DEGREES_LIB),-L$(51DEGREES_LIB))
+  USE_MATH         = implicit
+  ifneq ($(USE_51DEGREES_V4),)
+    USE_LIBATOMIC    = implicit
+  endif
 endif
 
 ifneq ($(USE_WURFL),)
-# Use WURFL_SRC and possibly WURFL_INC and WURFL_LIB to force path
-# to WURFL headers and libraries if needed.
-WURFL_INC = $(WURFL_SRC)
-WURFL_LIB = $(WURFL_SRC)
-OPTIONS_OBJS    += addons/wurfl/wurfl.o
-OPTIONS_CFLAGS  += $(if $(WURFL_INC),-I$(WURFL_INC))
-ifneq ($(WURFL_DEBUG),)
-OPTIONS_CFLAGS  += -DWURFL_DEBUG
-endif
-ifneq ($(WURFL_HEADER_WITH_DETAILS),)
-OPTIONS_CFLAGS  += -DWURFL_HEADER_WITH_DETAILS
-endif
-OPTIONS_LDFLAGS += $(if $(WURFL_LIB),-L$(WURFL_LIB)) -lwurfl
+  # Use WURFL_SRC and possibly WURFL_INC and WURFL_LIB to force path
+  # to WURFL headers and libraries if needed.
+  WURFL_INC = $(WURFL_SRC)
+  WURFL_LIB = $(WURFL_SRC)
+  OPTIONS_OBJS    += addons/wurfl/wurfl.o
+  OPTIONS_CFLAGS  += $(if $(WURFL_INC),-I$(WURFL_INC))
+  ifneq ($(WURFL_DEBUG),)
+    OPTIONS_CFLAGS  += -DWURFL_DEBUG
+  endif
+  ifneq ($(WURFL_HEADER_WITH_DETAILS),)
+    OPTIONS_CFLAGS  += -DWURFL_HEADER_WITH_DETAILS
+  endif
+  OPTIONS_LDFLAGS += $(if $(WURFL_LIB),-L$(WURFL_LIB)) -lwurfl
 endif
 
 ifneq ($(USE_SYSTEMD),)
-OPTIONS_LDFLAGS += -lsystemd
+  OPTIONS_LDFLAGS += -lsystemd
 endif
 
 ifneq ($(USE_PCRE)$(USE_STATIC_PCRE)$(USE_PCRE_JIT),)
-ifneq ($(USE_PCRE2)$(USE_STATIC_PCRE2)$(USE_PCRE2_JIT),)
-$(error cannot compile both PCRE and PCRE2 support)
-endif
-# PCREDIR is used to automatically construct the PCRE_INC and PCRE_LIB paths,
-# by appending /include and /lib respectively. If your system does not use the
-# same sub-directories, simply force these variables instead of PCREDIR. It is
-# automatically detected but can be forced if required (for cross-compiling).
-# Forcing PCREDIR to an empty string will let the compiler use the default
-# locations.
+  ifneq ($(USE_PCRE2)$(USE_STATIC_PCRE2)$(USE_PCRE2_JIT),)
+    $(error cannot compile both PCRE and PCRE2 support)
+  endif
+  # PCREDIR is used to automatically construct the PCRE_INC and PCRE_LIB paths,
+  # by appending /include and /lib respectively. If your system does not use the
+  # same sub-directories, simply force these variables instead of PCREDIR. It is
+  # automatically detected but can be forced if required (for cross-compiling).
+  # Forcing PCREDIR to an empty string will let the compiler use the default
+  # locations.
 
-# in case only USE_STATIC_PCRE/USE_PCRE_JIT were set
-USE_PCRE        := $(if $(USE_PCRE),$(USE_PCRE),implicit)
-PCRE_CONFIG    	:= pcre-config
-PCREDIR	        := $(shell $(PCRE_CONFIG) --prefix 2>/dev/null || echo /usr/local)
-ifneq ($(PCREDIR),)
-PCRE_INC        := $(PCREDIR)/include
-PCRE_LIB        := $(PCREDIR)/lib
-endif
+  # in case only USE_STATIC_PCRE/USE_PCRE_JIT were set
+  USE_PCRE    := $(if $(USE_PCRE),$(USE_PCRE),implicit)
+  PCRE_CONFIG := pcre-config
+  PCREDIR     := $(shell $(PCRE_CONFIG) --prefix 2>/dev/null || echo /usr/local)
+  ifneq ($(PCREDIR),)
+    PCRE_INC := $(PCREDIR)/include
+    PCRE_LIB := $(PCREDIR)/lib
+  endif
 
-ifeq ($(USE_STATIC_PCRE),)
-# dynamic PCRE
-OPTIONS_CFLAGS  += $(if $(PCRE_INC),-I$(PCRE_INC))
-OPTIONS_LDFLAGS += $(if $(PCRE_LIB),-L$(PCRE_LIB)) -lpcreposix -lpcre
-else
-# static PCRE
-OPTIONS_CFLAGS  += $(if $(PCRE_INC),-I$(PCRE_INC))
-OPTIONS_LDFLAGS += $(if $(PCRE_LIB),-L$(PCRE_LIB)) -Wl,-Bstatic -lpcreposix -lpcre -Wl,-Bdynamic
-endif
-endif
+  ifeq ($(USE_STATIC_PCRE),)
+    # dynamic PCRE
+    OPTIONS_CFLAGS  += $(if $(PCRE_INC),-I$(PCRE_INC))
+    OPTIONS_LDFLAGS += $(if $(PCRE_LIB),-L$(PCRE_LIB)) -lpcreposix -lpcre
+  else
+    # static PCRE
+    OPTIONS_CFLAGS  += $(if $(PCRE_INC),-I$(PCRE_INC))
+    OPTIONS_LDFLAGS += $(if $(PCRE_LIB),-L$(PCRE_LIB)) -Wl,-Bstatic -lpcreposix -lpcre -Wl,-Bdynamic
+  endif
+endif # USE_PCRE
 
 ifneq ($(USE_PCRE2)$(USE_STATIC_PCRE2)$(USE_PCRE2_JIT),)
-# in case only USE_STATIC_PCRE2/USE_PCRE2_JIT were set
-USE_PCRE2       := $(if $(USE_PCRE2),$(USE_PCRE2),implicit)
-PCRE2_CONFIG 	:= pcre2-config
-PCRE2DIR	:= $(shell $(PCRE2_CONFIG) --prefix 2>/dev/null || echo /usr/local)
-ifneq ($(PCRE2DIR),)
-PCRE2_INC       := $(PCRE2DIR)/include
-PCRE2_LIB       := $(PCRE2DIR)/lib
+  # in case only USE_STATIC_PCRE2/USE_PCRE2_JIT were set
+  USE_PCRE2    := $(if $(USE_PCRE2),$(USE_PCRE2),implicit)
+  PCRE2_CONFIG := pcre2-config
+  PCRE2DIR     := $(shell $(PCRE2_CONFIG) --prefix 2>/dev/null || echo /usr/local)
+  ifneq ($(PCRE2DIR),)
+    PCRE2_INC := $(PCRE2DIR)/include
+    PCRE2_LIB := $(PCRE2DIR)/lib
 
-ifeq ($(PCRE2_WIDTH),)
-PCRE2_WIDTH	= 8
-endif
+    ifeq ($(PCRE2_WIDTH),)
+      PCRE2_WIDTH = 8
+    endif
 
-ifneq ($(PCRE2_WIDTH),8)
-ifneq ($(PCRE2_WIDTH),16)
-ifneq ($(PCRE2_WIDTH),32)
-$(error PCRE2_WIDTH needs to be set to either 8,16 or 32)
-endif
-endif
-endif
+    ifneq ($(PCRE2_WIDTH),8)
+      ifneq ($(PCRE2_WIDTH),16)
+        ifneq ($(PCRE2_WIDTH),32)
+          $(error PCRE2_WIDTH needs to be set to either 8,16 or 32)
+        endif
+      endif
+    endif
 
+    PCRE2_LDFLAGS := $(shell $(PCRE2_CONFIG) --libs$(PCRE2_WIDTH) 2>/dev/null || echo -L/usr/local/lib -lpcre2-$(PCRE2_WIDTH))
 
-PCRE2_LDFLAGS	:= $(shell $(PCRE2_CONFIG) --libs$(PCRE2_WIDTH) 2>/dev/null || echo -L/usr/local/lib -lpcre2-$(PCRE2_WIDTH))
+    ifeq ($(PCRE2_LDFLAGS),)
+      $(error libpcre2-$(PCRE2_WIDTH) not found)
+    else
+      ifeq ($(PCRE2_WIDTH),8)
+        PCRE2_LDFLAGS += -lpcre2-posix
+      endif
+    endif
 
-ifeq ($(PCRE2_LDFLAGS),)
-$(error libpcre2-$(PCRE2_WIDTH) not found)
-else
-ifeq ($(PCRE2_WIDTH),8)
-PCRE2_LDFLAGS	+= -lpcre2-posix
-endif
-endif
-
-OPTIONS_CFLAGS	+= -DPCRE2_CODE_UNIT_WIDTH=$(PCRE2_WIDTH)
-OPTIONS_CFLAGS  += $(if $(PCRE2_INC), -I$(PCRE2_INC))
+    OPTIONS_CFLAGS  += -DPCRE2_CODE_UNIT_WIDTH=$(PCRE2_WIDTH)
+    OPTIONS_CFLAGS  += $(if $(PCRE2_INC), -I$(PCRE2_INC))
 
-ifneq ($(USE_STATIC_PCRE2),)
-PCRE2_LDFLAGS   := $(if $(PCRE2_LIB),-L$(PCRE2_LIB)) -Wl,-Bstatic -L$(PCRE2_LIB) $(PCRE2_LDFLAGS) -Wl,-Bdynamic
-else
-PCRE2_LDFLAGS   := $(if $(PCRE2_LIB),-L$(PCRE2_LIB)) -L$(PCRE2_LIB) $(PCRE2_LDFLAGS)
-endif
-
-endif
-endif
+    ifneq ($(USE_STATIC_PCRE2),)
+      PCRE2_LDFLAGS := $(if $(PCRE2_LIB),-L$(PCRE2_LIB)) -Wl,-Bstatic -L$(PCRE2_LIB) $(PCRE2_LDFLAGS) -Wl,-Bdynamic
+    else
+      PCRE2_LDFLAGS := $(if $(PCRE2_LIB),-L$(PCRE2_LIB)) -L$(PCRE2_LIB) $(PCRE2_LDFLAGS)
+    endif
+  endif # PCRE2DIR
+endif # USE_PCRE2
 
 ifneq ($(USE_NS),)
-OPTIONS_OBJS  += src/namespace.o
+  OPTIONS_OBJS  += src/namespace.o
 endif
 
 ifneq ($(USE_OT),)
-include addons/ot/Makefile
+  include addons/ot/Makefile
 endif
 
 # better keep this one close to the end, as several libs above may need it
@@ -831,17 +829,17 @@
 COPTS += $(DEBUG) $(OPTIONS_CFLAGS) $(ADDINC)
 
 ifneq ($(VERSION)$(SUBVERS)$(EXTRAVERSION),)
-COPTS += -DCONFIG_HAPROXY_VERSION=\"$(VERSION)$(SUBVERS)$(EXTRAVERSION)\"
+  COPTS += -DCONFIG_HAPROXY_VERSION=\"$(VERSION)$(SUBVERS)$(EXTRAVERSION)\"
 endif
 
 ifneq ($(VERDATE),)
-COPTS += -DCONFIG_HAPROXY_DATE=\"$(VERDATE)\"
+  COPTS += -DCONFIG_HAPROXY_DATE=\"$(VERDATE)\"
 endif
 
 ifneq ($(TRACE),)
-# if tracing is enabled, we want it to be as fast as possible
-TRACE_COPTS := $(filter-out -O0 -O1 -O2 -pg -finstrument-functions,$(COPTS)) -O3 -fomit-frame-pointer
-COPTS += -finstrument-functions
+  # if tracing is enabled, we want it to be as fast as possible
+  TRACE_COPTS := $(filter-out -O0 -O1 -O2 -pg -finstrument-functions,$(COPTS)) -O3 -fomit-frame-pointer
+  COPTS += -finstrument-functions
 endif
 
 #### Global link options
@@ -893,13 +891,13 @@
 	@exit 1
 else
 all: haproxy dev/flags/flags $(EXTRA)
-endif
-endif
+endif # obsolete targets
+endif # TARGET
 
 OBJS =
 
 ifneq ($(EXTRA_OBJS),)
-OBJS += $(EXTRA_OBJS)
+  OBJS += $(EXTRA_OBJS)
 endif
 
 OBJS += src/mux_h2.o src/mux_fcgi.o src/mux_h1.o src/tcpcheck.o               \
@@ -936,7 +934,7 @@
         src/ebtree.o src/hash.o src/dgram.o src/version.o
 
 ifneq ($(TRACE),)
-OBJS += src/calltrace.o
+  OBJS += src/calltrace.o
 endif
 
 # Used only for forced dependency checking. May be cleared during development.
@@ -970,7 +968,7 @@
 .build_opts: $(build_opts)
 else
 .build_opts:
-endif
+endif # reg-tests
 
 haproxy: $(OPTIONS_OBJS) $(OBJS)
 	$(cmd_LD) $(LDFLAGS) -o $@ $^ $(LDOPTS)