add mac target

Makefile.defs

@@ -122,6 +122,10 @@ else ifeq ($(TARGET), debian-armhf)
 	CHOST?=arm-linux-gnueabihf
 	export SDL=1
 	export DEBIAN_CROSS=1
+else ifeq ($(TARGET), macos)
+	export SDL=1
+	export MACOS=1
+	export EMULATE_READER=1
 else ifeq ($(TARGET), android)
 	export ANDROID=1
 	export PATH:=$(ANDROID_TOOLCHAIN)/bin:$(PATH)
@@ -448,6 +452,10 @@ ifdef DEBIAN
 	HOST_ARCH:=-mtune=generic
 endif
 
+ifdef MACOS
+	HOST_ARCH:=-mtune=generic
+endif
+
 # Anything below GCC 6 gets to be forcefully switched to decent standards, because some of our deps require C11 & C++11 support.
 # NOTE: Technically, this also means we require Clang >= 3.2, but that should more or less hold true on our end, because that's truly ancient.
 # Tests heavily inspired from Linux's build system ;).