MdeModulePkg/RegularExpressionDxe: Optimize the code infrastructure

OnigurumaIntrinsics.c is now not used. So the implement of function
'memcpy' is now not., which causes build failure with CLANG9 and
XCODE. I remove OnigurumaIntrinsics.c and move the necessary function
implement to OnigurumaUefiPort.c/h.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>

MdeModulePkg/Universal/RegularExpressionDxe/OnigurumaUefiPort.c

@@ -86,3 +86,13 @@ void * realloc (void *ptr, size_t size)
   return NULL;
 }
 
+void* memcpy (void *dest, const void *src, unsigned int count)
+{
+  return CopyMem (dest, src, (UINTN)count);
+}
+
+void* memset (void *dest, char ch, unsigned int count)
+{
+  return SetMem (dest, ch, count);
+}
+