message: Further fixes to zh_{CN,TW} normalization
  This fixes roundtripping and thus normalization in
  See also
diff: @@ -216,6 +216,11 @@ const DisplayNamesData& GetDisplayNamesData()
  std::string DoGetLanguageTag(const Language& lang)
  {
  + if (lang.Code() == "zh_CN")
  + return "zh-Hans";
  + else if (lang.Code() == "zh_TW")
  + return "zh-Hant";
  +
  auto l = lang.Lang();
  auto c = lang.Country();
  auto v = lang.Variant();
  