cmake HAVE_ARMV8_SIMD examples

ceph/ceph cmake/modules/SIMDExt.cmake :47 

CHECK_C_COMPILER_FLAG(-march=armv8-a+simd HAVE_ARMV8_SIMD)

ceph/ceph src/compressor/zlib/CMakeLists.txt :45 

elseif(HAVE_ARMV8_SIMD)