CryptoPkg/BaseCryptLib: Fix Build Warning issue in PEI Module

CryptoPkg/BaseCryptLib: Fix Build Warning issue in PEI Module

The memory free operation is empty function in PEI. The compiler
optimization will bring the build warning in openssl/crypto/mem.c:
      warning C4718: 'CRYPTO_free': recursive call has no side
                     effects, deleting
This patch uses '/wd4718' to silence the build warning for PEI
module building.

Cc: Ting Ye <ting.ye@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qin Long <qin.long@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>