GO linux 底下编译安卓

Linux下编译安卓：
注意，需要下载Android NDK

	CGO_ENABLED=1 
	GOOS=android 
	GOARCH=arm64 
	CC_FOR_TARGET=$NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android21-clang 
	CC=$NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android21-clang