Add ios-arm64 build target

Makefile

@@ -80,9 +80,13 @@ ifeq ($(IOSSDK),)
    IOSSDK := $(shell xcodebuild -version -sdk iphoneos Path)
 endif
 
-   CC = cc -arch armv7 -isysroot $(IOSSDK)
+	ifeq ($(platform),ios-arm64)
+		CC = cc -arch arm64 -isysroot $(IOSSDK)
+	else
+		CC = cc -arch armv7 -isysroot $(IOSSDK)
+	endif
    CC_AS = perl ./tools/gas-preprocessor.pl $(CC)
-ifeq ($(platform),ios9)
+ifeq ($(platform),$(filter $(platform),ios9 ios-arm64))
    CC += -miphoneos-version-min=8.0
    CC_AS += -miphoneos-version-min=8.0
    PLATFORM_DEFINES := -miphoneos-version-min=8.0