Correct the wrong '?' character to '-', and add check DestinationBuffer == SourceBuffer for CompareMem functions in all BaseMemory library instances.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@5831 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BaseMemoryLibMmx/CompareMemWrapper.c

@@ -55,7 +55,7 @@ CompareMem (
   IN UINTN       Length
   )
 {
-  if (0 == Length) {
+  if (Length == 0 || DestinationBuffer == SourceBuffer) {
     return 0;
   }
   ASSERT (DestinationBuffer != NULL);