Merge pull request #5427 from jtattermusch/fix_gcc44_string_decode

Don't fail when generating report.xml on gcc4.4

tools/run_tests/report_utils.py

@@ -47,7 +47,7 @@ def _filter_msg(msg, output_format):
     # that make XML report unparseable.
     filtered_msg = filter(
         lambda x: x in string.printable and x != '\f' and x != '\v',
-        msg.decode(errors='ignore'))
+        msg.decode('UTF-8', 'ignore'))
     if output_format == 'HTML':
       filtered_msg = filtered_msg.replace('"', '"')
     return filtered_msg