os.environ contains all environment variables uppercase on Windows which
cause the key in the self.MacroDictionary is uppercase, but the real
variable name maybe mixed case, eg:WINSDK81x86, then we can't find the
variable in the self.MacroDictionary.
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>
18ca2fec97