MdePkg BaseMemoryLib: Add assembly implementation of API IsZeroBuffer()

Add the implementation of API IsZeroBuffer() via assembly for the
following library instances:
BaseMemoryLibMmx
BaseMemoryLibOptDxe
BaseMemoryLibOptPei
BaseMemoryLibRepStr

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

MdePkg/Library/BaseMemoryLibRepStr/MemLibInternals.h

@@ -9,7 +9,7 @@
     BaseMemoryLibOptDxe
     BaseMemoryLibOptPei
 
-  Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -231,4 +231,21 @@ InternalMemScanMem64 (
   IN      UINT64                    Value
   );
 
+/**
+  Checks whether the contents of a buffer are all zeros.
+
+  @param  Buffer  The pointer to the buffer to be checked.
+  @param  Length  The size of the buffer (in bytes) to be checked.
+
+  @retval TRUE    Contents of the buffer are all zeros.
+  @retval FALSE   Contents of the buffer are not all zeros.
+
+**/
+BOOLEAN
+EFIAPI
+InternalMemIsZeroBuffer (
+  IN CONST VOID  *Buffer,
+  IN UINTN       Length
+  );
+
 #endif