HACK: support LanguageStandard and LanguageStandard_C in gyp

Author: targos

tools/gyp/pylib/gyp/MSVSSettings.py

@@ -799,6 +799,8 @@ def _ValidateSettings(validators, settings, stderr):
 _MSBuildOnly(_compile, "TrackerLogDirectory", _folder_name)
 _MSBuildOnly(_compile, "TreatSpecificWarningsAsErrors", _string_list)  # /we
 _MSBuildOnly(_compile, "UseUnicodeForAssemblerListing", _boolean)  # /FAu
+_MSBuildOnly(_compile, "LanguageStandard", _string)
+_MSBuildOnly(_compile, "LanguageStandard_C", _string)
 
 # Defines a setting that needs very customized processing
 _CustomGeneratePreprocessedFile(_compile, "GeneratePreprocessedFile")