wayland: Emit geometryChanged signal if transform changes

If the output transform changes, the geometry may change as well;
otherwise qpa may not call QWindowSystemInterface::handleScreenGeometryChange()
with the corresponding platform screen.

src/abstract_wayland_output.cpp

@@ -270,6 +270,7 @@ void AbstractWaylandOutput::setTransformInternal(Transform transform)
         m_transform = transform;
         Q_EMIT transformChanged();
         Q_EMIT modeChanged();
+        Q_EMIT geometryChanged();
     }
 }