MdeModulePkg DxeCore: Enhance MemoryAttributesTable installation

Current MemoryAttributesTable will be installed on ReadyToBoot event
at TPL_NOTIFY level, it maybe incorrect when PcdHiiOsRuntimeSupport
= TRUE as HiiDatabaseDxe will have runtime memory allocation for HII
OS runtime support on and after ReadyToBoot. The issue was exposed at
http://article.gmane.org/gmane.comp.bios.edk2.devel/10125.

To make sure the correctness of MemoryAttributesTable, this patch is
to enhance MemoryAttributesTable installation to install
MemoryAttributesTable on ReadyToBoot event at TPL_CALLBACK - 1 level
to make sure it is at the last of ReadyToBoot event, and also hook
runtime memory allocation after ReadyToBoot.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

MdeModulePkg/Core/Dxe/DxeMain.h

@@ -276,6 +276,8 @@ extern EFI_RUNTIME_SERVICES                     *gDxeCoreRT;
 extern EFI_DXE_SERVICES                         *gDxeCoreDS;
 extern EFI_HANDLE                               gDxeCoreImageHandle;
 
+extern BOOLEAN                                  gMemoryMapTerminated;
+
 extern EFI_DECOMPRESS_PROTOCOL                  gEfiDecompress;
 
 extern EFI_RUNTIME_ARCH_PROTOCOL                *gRuntime;
@@ -2858,6 +2860,16 @@ CoreInitializeMemoryAttributesTable (
   VOID
   );
 
+/**
+  Install MemoryAttributesTable on memory allocation.
+
+  @param[in] MemoryType EFI memory type.
+**/
+VOID
+InstallMemoryAttributesTableOnMemoryAllocation (
+  IN EFI_MEMORY_TYPE    MemoryType
+  );
+
 /**
   Insert image record.