MdeModulePkg/RegularExpressionDxe: Make oniguruma a submodule in edk2.

Use submodule way to access oniguruma. And upgrade oniguruma
version from v6.9.3 to v6.9.4_mark1.
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2073

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

MdeModulePkg/Universal/RegularExpressionDxe/OnigurumaIntrinsics.c

@@ -0,0 +1,48 @@
+/** @file
+
+  Provide intrinsics within Oniguruma
+
+  (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
+  Copyright (c) 2020, Intel Corporation. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Library/BaseMemoryLib.h>
+
+//
+// From CryptoPkg/IntrinsicLib
+//
+
+/* Copies bytes between buffers */
+#pragma function(memcpy)
+void * memcpy (void *dest, const void *src, unsigned int count)
+{
+  return CopyMem (dest, src, (UINTN)count);
+}
+
+/* Sets buffers to a specified character */
+#pragma function(memset)
+void * memset (void *dest, char ch, unsigned int count)
+{
+  //
+  // NOTE: Here we use one base implementation for memset, instead of the direct
+  //       optimized SetMem() wrapper. Because the IntrinsicLib has to be built
+  //       without whole program optimization option, and there will be some
+  //       potential register usage errors when calling other optimized codes.
+  //
+
+  //
+  // Declare the local variables that actually move the data elements as
+  // volatile to prevent the optimizer from replacing this function with
+  // the intrinsic memset()
+  //
+  volatile UINT8  *Pointer;
+
+  Pointer = (UINT8 *)dest;
+  while (count-- != 0) {
+    *(Pointer++) = ch;
+  }
+
+  return dest;
+}