This adds AARCH64 support to BaseMemoryLibOptDxe, based on the cortex-strings library. All string routines are accelerated except ScanMem16, ScanMem32, ScanMem64 and IsZeroBuffer, which can wait for another day. (Very few occurrences exist in the codebase) Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Liming Gao <liming.gao@intel.com>