Update Makefile.arm64
Update Makefile.arm64

Added -march and -mtune flags for EMAG processors when GCC 9 or later
xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS