MdePkg/BaseMemoryLibOptDxe ARM|AARCH64: implement accelerated GUID functions

MdePkg/BaseMemoryLibOptDxe ARM|AARCH64: implement accelerated GUID functions

As reported by Vishal, CompareGuid() is a hotspot, and switching from
BaseMemoryLibStm in ArmPkg/ to BaseMemoryLibOptDxe causes a noticeable
performance regression due to the fact that BaseMemoryLibOptDxe uses
unaligned accessors explicitly to implement CompareGuid() and the related
functions.

Since BaseMemoryLibOptDxe on ARM and AARCH64 can only be used in contexts
where unaligned accesses are allowed, reimplement these functions for ARM
and AARCH64 specifically, using wide accessors that can tolerate any
misalignment.

Reported-by: "Oliyil Kunnil, Vishal" <vishalo@qti.qualcomm.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>