Improved loplugin:stringconstant (now that GCC 7 supports it): i18nlangtag

Change-Id: I04e013d61cc6b85fe6234f7d2934f22cc6c266e9
Reviewed-on: https://gerrit.libreoffice.org/76671
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

i18nlangtag/source/languagetag/languagetag.cxx

@@ -2344,7 +2344,7 @@ LanguageTag & LanguageTag::makeFallback()
 OUString LanguageTag::getBcp47MS() const
 {
     if (getLanguageType() == LANGUAGE_SPANISH_DATED)
-        return OUString("es-ES_tradnl");
+        return "es-ES_tradnl";
     return getBcp47();
 }