Fix test compilation when QT_NO_CURSOR is defined

The implicitConstruction() test case will fail to compile if QCursor is
unavailable.

Change-Id: If26743995505a48da648a2fa2a498debec91c933
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Skip tst_QGraphicsProxyWidget::popup_subwidget on Windows.

Task-number: QTBUG-33213
Change-Id: I1c8daa3a859f9d0d760054f1d8934abd84f62f0d
Reviewed-by: Andreas Aardal Hanssen <andreas@hanssen.name>