MdeModulePkg PiSmmCore: Enhance SMM FreePool to catch buffer overflow

MdeModulePkg PiSmmCore: Enhance SMM FreePool to catch buffer overflow

This solution is equivalent to DXE core.

AllocatePool() allocates POOL_TAIL after the buffer.
This POOL_TAIL is checked at FreePool().
If the there is buffer overflow, the issue can be caught at FreePool().

This patch could also handle the eight-byte aligned allocation
requirement. The discussion related to the eight-byte aligned
allocation requirement is at
https://lists.01.org/pipermail/edk2-devel/2017-April/009995.html.

According to the PI spec (Vol 4, Section 3.2 SmmAllocatePool()):
The SmmAllocatePool() function ... All allocations are eight-byte aligned.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>