better use application settings

It doesn't really matter, just saves some cycles looking up the system
locale.

Change-Id: I8895593b445c49f167f26bcbf510c12a3c25e1d4

cui/source/dialogs/about.cxx

@@ -281,7 +281,7 @@ OUString AboutDialog::GetVersionString()
 
     OUString sBuildId = GetBuildId();
 
-    OUString aLocaleStr = LanguageTag( LANGUAGE_SYSTEM).getBcp47() + " (" + GetLocaleString() + ")";
+    OUString aLocaleStr = Application::GetSettings().GetLanguageTag().getBcp47() + " (" + GetLocaleString() + ")";
 
     if (!sBuildId.trim().isEmpty())
     {