clean up all of eight BaseMemoryLib instances in MdePkg with the following updates:

clean up all of eight BaseMemoryLib instances in MdePkg with the following updates:
1.	Remove .intel_syntax directives in GCC assembly files. All these assembly files have been updated to use the preferred syntax for GAS
2.	Correct the incorrect comments for internal worker functions for SetMemXX() and ScanMemXX(). The Length parameter is actually the counter of 16-bit, 32-bit or 64-bit value.
3.	Simplify the logic in ZeroMemoryWrapper.c for BaseMemoryLibOptPei instance to remove the conditional statement for zero length. This logic is already covered by worker function InternalMemZeroMem().
4.	Cleanup all the Wrapper C files in BaseMemoryLib instances. They are supposed to be shared by all these 8 BaseMemoryLib instances, but are out-of-sync after some maintenance. This patch re-syncs them and makes them exactly the same.
5.	Cleanup MemLibInternal.h so that it is shared by 6 BaseMemoryLib instance except for PeiMemoryLib and UefiMemoryLib.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9041 6f19259b-4bc3-4df7-8a09-765794883524