Old versions of GCC do not recognize this flag

--- makefile_include.mk.orig
+++ makefile_include.mk
@@ -95,7 +95,7 @@
 LTM_CFLAGS += -Wno-shadow
 endif
 ifeq ($(PLATFORM), Darwin)
-LTM_CFLAGS += -Wno-nullability-completeness
+# LTM_CFLAGS += -Wno-nullability-completeness
 endif
 ifeq ($(PLATFORM), CYGWIN)
 LIBTOOLFLAGS += -no-undefined