They may be referenced from somewhere else, and
there's no reason not to keep them alive while
the MenuItem is alive.

Task-number: QTBUG-37554
Change-Id: Idaab616c856348c0b7eeb1a2e9fdc5bfc3f8a5fd
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>