Widgets: Never revoke focus by click on focused widget.

When clicking on a widget currently focused, w/o having Qt::ClickFocus
set as focus policy, the focus should stay on the widget and not get
propagated to the widget's parent.

Task-number: QTBUG-34042

Change-Id: I53f1153829cc7228de02a90e38125b5cf4ee5008
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>