Fix handling of non-latin1 shortcuts

This patch enables non-latin1 shortcut handling on Qt5/X11.

Task-number: QTBUG-32274
Change-Id: Ia084258b956128ffade8eddfbcb18af334d79a59
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>