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/Ecc/Xml/XmlRoutines.py

@@ -214,7 +214,7 @@ def XmlParseFile(FileName):
         Dom = xml.dom.minidom.parse(XmlFile)
         XmlFile.close()
         return Dom
-    except Exception, X:
+    except Exception as X:
         print X
         return ""