WinRT: set orientation update mask to native orientation by default

This aligns with the other mobile platforms.

Task-number: QTBUG-38691
Change-Id: I7b9b70a1182c0e53f997cae111ec46b5161b0b48
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>

src/plugins/platforms/winrt/qwinrtscreen.cpp

@@ -496,6 +496,7 @@ QWinRTScreen::QWinRTScreen(ICoreWindow *window)
 
         // Set initial orientation
         onOrientationChanged(0);
+        setOrientationUpdateMask(m_nativeOrientation);
 
         m_displayProperties->add_OrientationChanged(Callback<IDisplayPropertiesEventHandler>(this, &QWinRTScreen::onOrientationChanged).Get(),
                                                     &m_tokens[QEvent::OrientationChange]);