QWidget: delete 'extra' in dtor

Call d->deleteExtra() in dtor of QWidget to make sure it's cleaned up
before QWidgetPrivate calls it which might access the already deleted
QWidget through deleteTLSysExtra() /
QWindowContainer::toplevelAboutToBeDestroyed(q).

Amends 006cbf6.

Task-number: QTBUG-130932
Change-Id: I9109072a457cc01abd5d1b4e844a3ed3309d942b
Reviewed-by: Tor Arne Vestbø <[email protected]>
Reviewed-by: Volker Hilsheimer <[email protected]>
(cherry picked from commit 482c41f)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>
(cherry picked from commit a6a0a38)

src/widgets/kernel/qwidget.cpp

@@ -1581,6 +1581,7 @@ QWidget::~QWidget()
 #if QT_CONFIG(graphicseffect)
     delete d->graphicsEffect;
 #endif
+    d->deleteExtra();
 
     d->isWidget = false;
 }