Fix showFullScreen for QWindow

If the setWindowState is called in a early stage,
where the window is not yet shown, the fullscreen
flag is cached in the QWindow. Then in the call to
setVisible(true) the window gets generated, but the
fullscreen is not handled there. So set the state
while window is generated.

Change-Id: I0ea53ed8a2465da6a9973d84fb4579381543e89b
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/plugins/platforms/windows/qwindowswindow.cpp

@@ -693,7 +693,7 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const WindowData &data) :
     m_data(data),
     m_flags(0),
     m_hdc(0),
-    m_windowState(aWindow->windowState()),
+    m_windowState(Qt::WindowNoState),
     m_opacity(1.0),
     m_mouseGrab(false),
     m_cursor(QWindowsScreen::screenOf(aWindow)->windowsCursor()->standardWindowCursor()),
@@ -721,6 +721,7 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const WindowData &data) :
             break;
         }
     }
+    setWindowState(aWindow->windowState());
 }
 
 QWindowsWindow::~QWindowsWindow()