Add back support for /Gv now that gyp-win64 has VS2013

pylib/gyp/MSVSSettings_test.py

 #!/usr/bin/env python
 
 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unit tests for the MSVSSettings.py file."""
 
 import StringIO
 import unittest
@@ skipping 249 matching lines @@
              'UseFAT32Workaround': 'true',
              'UseUnicodeResponseFiles': 'true',
              'VerboseOutput': 'true'}},
         self.stderr)
     self._ExpectedWarnings([
         'Warning: for VCCLCompilerTool/BasicRuntimeChecks, '
         'index value (5) not in expected range [0, 4)',
         'Warning: for VCCLCompilerTool/BrowseInformation, '
         "invalid literal for int() with base 10: 'fdkslj'",
         'Warning: for VCCLCompilerTool/CallingConvention, '
-        'index value (-1) not in expected range [0, 3)',
+        'index value (-1) not in expected range [0, 4)',
         'Warning: for VCCLCompilerTool/DebugInformationFormat, '
         'converted value for 2 not specified.',
         'Warning: unrecognized setting VCCLCompilerTool/Enableprefast',
         'Warning: unrecognized setting VCCLCompilerTool/ZZXYZ',
         'Warning: for VCLinkerTool/TargetMachine, '
         'converted value for 2 not specified.',
         'Warning: unrecognized setting VCMIDLTool/notgood',
         'Warning: unrecognized setting VCResourceCompilerTool/notgood2',
         'Warning: for VCManifestTool/UpdateFileHashes, '
         "expected bool; got 'truel'"
@@ skipping 1193 matching lines @@
         }
     actual_msbuild_settings = MSVSSettings.ConvertToMSBuildSettings(
         msvs_settings,
         self.stderr)
     self.assertEqual(expected_msbuild_settings, actual_msbuild_settings)
     self._ExpectedWarnings([])
 
 
 if __name__ == '__main__':
   unittest.main()