Share the qml engine as a qApp property
use this for weird kcms that are still qwidget but have an internal QQuickWidget, so that they can share the qqmlengine
this works around BUG: 488326
(cherry picked from commit 1021059c)
deda2c74 Share the qml engine as a qApp property
Co-authored-by: Marco Martin notmart@gmail.com