Fixed makefile to work for various different gcc versions on OSX (from Craig Berry)

makefile

@@ -80,6 +80,10 @@ ifeq ($(WIN32),)  #*nix Environments (&& cygwin)
     ifeq (Darwin,$(OSTYPE))
       OSNAME = OSX
       LIBEXT = dylib
+      # OSX's XCode gcc doesn't support LTO, but gcc built to explicitly enable it will work
+      ifeq (,$(shell $(GCC) -v /dev/null 2>&1 | grep '--enable-lto'))
+        LTO_EXCLUDE_VERSIONS += $(GCC_VERSION)
+      endif
     else
       ifeq (Linux,$(OSTYPE))
         LIBPATH := $(sort $(foreach lib,$(shell /sbin/ldconfig -p | grep ' => /' | sed 's/^.* => //'),$(dir $(lib))))