BUILD/MINOR: auth: enabling for osx

macOS supports this but as part of libc.
Little typo fix while here.
diff --git a/Makefile b/Makefile
index ec15cbd..5fff435 100644
--- a/Makefile
+++ b/Makefile
@@ -355,7 +355,7 @@
 # Mac OS/X
 ifeq ($(TARGET),osx)
   set_target_defaults = $(call default_opts, \
-    USE_POLL USE_TPROXY USE_KQUEUE)
+    USE_POLL USE_TPROXY USE_LIBCRYPT USE_KQUEUE)
   EXPORT_SYMBOL  = -export_dynamic
 endif
 
@@ -452,8 +452,10 @@
 OPTIONS_CFLAGS += $(foreach opt,$(use_opts),$(if $($(opt)),-D$(opt),))
 
 ifneq ($(USE_LIBCRYPT),)
+ifneq ($(TARGET),osx)
 OPTIONS_LDFLAGS += -lcrypt
 endif
+endif
 
 ifneq ($(USE_SLZ),)
 # Use SLZ_INC and SLZ_LIB to force path to zlib.h and libz.{a,so} if needed.