Windows: Use DND effect chosen in DragEnter/Move for Drop.

The value of pdwEffect passed to IOleDropTarget::Drop() is always
the one with which the drag was initiated.

Task-number: QTBUG-43466
Change-Id: I045fef634b55d4f113b393aa0ad4aa15d37db372
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

src/plugins/platforms/windows/qwindowsdrag.cpp

@@ -626,7 +626,7 @@ QWindowsOleDropTarget::Drop(LPDATAOBJECT pDataObj, DWORD grfKeyState,
     const QPlatformDropQtResponse response =
         QWindowSystemInterface::handleDrop(m_window, windowsDrag->dropData(),
                                            m_lastPoint / QWindowsScaling::factor(),
-                                           translateToQDragDropActions(*pdwEffect));
+                                           translateToQDragDropActions(m_chosenEffect));
 
     if (response.isAccepted()) {
         const Qt::DropAction action = response.acceptedAction();