Don't pass NULL to wxDir, rather hop over when trying to find dir with translation

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64985 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/translation.cpp

@@ -1741,6 +1741,8 @@ wxArrayString wxFileTranslationsLoader::GetAvailableTranslations(const wxString&
           i != prefixes.end();
           ++i )
     {
+        if (i->length() == 0)
+            continue;
         wxDir dir;
         if ( !dir.Open(*i) )
             continue;