Add a binary for Apple Silicon (M1) (#268)

Makefile

@@ -1,6 +1,8 @@
 
 include Makefile.common
 
+$(info OS_NAME:$(OS_NAME), OS_ARCH:$(OS_ARCH))
+
 MVN:=mvn
 SBT:=./sbt
 

Makefile.common

@@ -45,7 +45,7 @@ endif
 
 # os=Default is meant to be generic unix/linux
 
-known_os_archs := Linux-x86 Linux-x86_64 Linux-arm Linux-armv6 Linux-armv7 Linux-android-arm Linux-aarch64 Linux-ppc Linux-ppc64 Linux-ppc64le Linux-s390 Linux-s390x Mac-x86 Mac-x86_64 FreeBSD-x86_64 Windows-x86 Windows-x86_64 SunOS-x86 SunOS-sparc SunOS-x86_64 AIX-ppc AIX-ppc64
+known_os_archs := Linux-x86 Linux-x86_64 Linux-arm Linux-armv6 Linux-armv7 Linux-android-arm Linux-aarch64 Linux-ppc Linux-ppc64 Linux-ppc64le Linux-s390 Linux-s390x Mac-x86 Mac-x86_64 Mac-aarch64 FreeBSD-x86_64 Windows-x86 Windows-x86_64 SunOS-x86 SunOS-sparc SunOS-x86_64 AIX-ppc AIX-ppc64
 os_arch := $(OS_NAME)-$(OS_ARCH)
 IBM_JDK_7 := $(findstring IBM, $(shell $(JAVA) -version 2>&1 | grep IBM | grep "JRE 1.7"))
 
@@ -250,6 +250,12 @@ Mac-x86_64_LINKFLAGS := -dynamiclib
 Mac-x86_64_LIBNAME   := libsnappyjava.dylib
 Mac-x86_64_SNAPPY_FLAGS  :=
 
+Mac-aarch64_CXX       := c++ -arch arm64
+Mac-aarch64_STRIP     := strip -x
+Mac-aarch64_CXXFLAGS  := -Ilib/inc_mac -I$(JAVA_HOME)/include -O2 -fPIC -mmacosx-version-min=10.7 -fvisibility=hidden -stdlib=libc++ -std=c++11
+Mac-aarch64_LINKFLAGS := -dynamiclib
+Mac-aarch64_LIBNAME   := libsnappyjava.dylib
+
 FreeBSD-x86_64_CXX          := $(CROSS_PREFIX)g++
 FreeBSD-x86_64_STRIP        := $(CROSS_PREFIX)strip
 FreeBSD-x86_64_CXXFLAGS     := -I$(JAVA_HOME)/include -Ilib/inc_mac -O2 -fPIC -fvisibility=hidden -std=c++11