Use correct Makefile on powerpc64
Use correct Makefile on powerpc64

FreeBSD uses powerpc64 name for POWER architecture. Use correct Makefile for this platform.
xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS