Merge branch 'msw-locale'

Fixes for setting locale under MSW when using older compilers and minor
simplifications and optimizations in wxLocale code.

See https://github.com/wxWidgets/wxWidgets/pull/517

interface/wx/intl.h

@@ -55,8 +55,13 @@ struct wxLanguageInfo
     /// @onlyfor{wxmsw}
     wxUint32 GetLCID() const;
 
-    /// Return the locale name corresponding to this language usable with
-    /// @c setlocale() on the current system.
+    /**
+        Return the locale name corresponding to this language usable with
+        @c setlocale() on the current system.
+
+        If setting locale for this language is not supported, the returned
+        string is empty.
+     */
     wxString GetLocaleName() const;
 };