This patch remove the hardcoded /bin/bash for PreBuild/PostBuild scripts. Cc: Liming Gao <liming.gao@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com>