BaseTools: Refactor python except statements

Convert "except ... ," to "except ... as" to be compatible with python3.
Based on "futurize -f lib2to3.fixes.fix_except"

Contributed-under: TianoCore Contribution Agreement 1.1
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>

BaseTools/Source/Python/Workspace/InfBuildData.py

@@ -1121,7 +1121,7 @@ class InfBuildData(ModuleBuildClassObject):
                     else:
                         try:
                             Pcd.DefaultValue = ValueExpressionEx(Pcd.DefaultValue, Pcd.DatumType, _GuidDict)(True)
-                        except BadExpression, Value:
+                        except BadExpression as Value:
                             EdkLogger.error('Parser', FORMAT_INVALID, 'PCD [%s.%s] Value "%s", %s' %(TokenSpaceGuid, PcdRealName, Pcd.DefaultValue, Value),
                                             File=self.MetaFile, Line=LineNo)
                     break