[Patch 2/4] CryptoPkg: Fix possible unresolved external symbol issue.

[Qin Long <qin.long@intel.com>]

The compiler (visual studio) may optimize some explicit strcmp call
to use the intrinsic memcmp call. In CrtLibSupport.h, we just use
 #define to mapping memcmp to CompareMem API. So in Link phase, this
kind of intrinsic optimization will cause the "unresolved external
symbol" error. For example:
    OpensslLib.lib(v3_utl.obj) : error LNK2001:
                               unresolved external symbol _memcmp

This patch will keep the memcmp mapping, and provide extra Intrinsic
memcmp wrapper to satisfy the symbol link.

Cc: Ting Ye <ting.ye@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qin Long <qin.long@intel.com>
---
 CryptoPkg/Include/CrtLibSupport.h                 | 1 +
 CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/CryptoPkg/Include/CrtLibSupport.h b/CryptoPkg/Include/CrtLibSupport.h
index ddf7784a37..7f1ec12302 100644
--- a/CryptoPkg/Include/CrtLibSupport.h
+++ b/CryptoPkg/Include/CrtLibSupport.h
@@ -133,6 +133,7 @@ void           *malloc     (size_t);
 void           *realloc    (void *, size_t);
 void           free        (void *);
 void           *memset     (void *, int, size_t);
+int            memcmp      (const void *, const void *, size_t);
 int            isdigit     (int);
 int            isspace     (int);
 int            isxdigit    (int);
diff --git a/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c b/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
index e8a76d07ff..33489aa6f4 100644
--- a/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
+++ b/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
@@ -46,6 +46,12 @@ void * memset (void *dest, char ch, unsigned int count)
   return dest;
 }
 
+/* Compare characters in two buffers. */
+int memcmp (const void *buf1, const void *buf2, unsigned int count)
+{
+  return (int)(CompareMem(buf1,buf2,(UINTN)(count)));
+}
+
 int strcmp (const char *s1, const char *s2)
 {
   return (int)AsciiStrCmp(s1, s2);
-- 
2.12.2.windows.1