MdeModulePkg/BrotliCustomDecompressLib: Make brotli a submodule

Use submodule way to access brotli in MdeModulePkg based on
brotli version 666c3280cc11dc433c303d79a83d4ffbdd12cc8d.
The newly added BrotliDecUefiSupport.h/.c are used by directory
'brotli'.
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2559

Cc: Liming Gao <liming.gao@intel.com>
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: Liming Gao <liming.gao@intel.com>

MdeModulePkg/Library/BrotliCustomDecompressLib/BrotliDecompressLibInternal.h

@@ -3,7 +3,7 @@
 
   Allows BROTLI code to build under UEFI (edk2) build environment
 
-  Copyright (c) 2017 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2017 - 2020, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -12,12 +12,9 @@
 #define __BROTLI_DECOMPRESS_INTERNAL_H__
 
 #include <PiPei.h>
-#include <Library/BaseLib.h>
-#include <Library/BaseMemoryLib.h>
-#include <Library/DebugLib.h>
 #include <Library/ExtractGuidedSectionLib.h>
-#include <brotli/types.h>
-#include <brotli/decode.h>
+#include <brotli/c/include/brotli/types.h>
+#include <brotli/c/include/brotli/decode.h>
 
 typedef struct
 {
@@ -30,20 +27,6 @@ typedef struct
 #define BROTLI_DECODE_MAX    8
 #define BROTLI_SCRATCH_MAX   16
 
-#define memcpy                      CopyMem
-#define memmove                     CopyMem
-#define memset(dest,ch,count)       SetMem(dest,(UINTN)(count),(UINT8)(ch))
-
-VOID *
-BrDummyMalloc (
-  IN size_t   Size
-  );
-
-VOID
-BrDummyFree (
-  IN VOID *   Ptr
-  );
-
 EFI_STATUS
 EFIAPI
 BrotliUefiDecompressGetInfo (