BUILD: add USE_LUA to BUILD_OPTIONS when it's used
haproxy -vv doesn't indicate that USE_LUA was specified at compilation time.
This is caused by the Makefile, which doesn't update BUILD_OPTIONS.
diff --git a/Makefile b/Makefile
index 2517b37..cc4b241 100644
--- a/Makefile
+++ b/Makefile
@@ -595,6 +595,7 @@
ifneq ($(USE_LUA),)
check_lua_lib = $(shell echo "int main(){}" | $(CC) -o /dev/null -x c - $(2) -l$(1) 2>/dev/null && echo $(1))
+BUILD_OPTIONS += $(call ignore_implicit,USE_LUA)
OPTIONS_CFLAGS += -DUSE_LUA $(if $(LUA_INC),-I$(LUA_INC))
LUA_LD_FLAGS := $(if $(LUA_LIB),-L$(LUA_LIB))
ifeq ($(LUA_LIB_NAME),)