Save up a bunch of stat() calls on application start
We are checking if every language known to us is present just to make
sure that we have more than one and show the dialog entry.
Always showing it is not a big deal and we'd save up this penalty at
Reviewers: Frameworks, dfaure, asturmlechner
Reviewed By: dfaure, asturmlechner
Subscribers: ltoscano, aacid, dfaure, elvisangelaccio, broulik
Differential Revision: https://phabricator.kde.org/D7230