Android: Make QtWindow package private

Change-Id: I0231193c3118619b4d2fc9f4e7f0f85ddd0b41b8
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
(cherry picked from commit 1f2570976e3b337a7f9eefea0c6937e943b7887a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/android/jar/src/org/qtproject/qt/android/QtWindow.java

@@ -13,7 +13,7 @@ import android.view.ViewGroup;
 
 import java.util.HashMap;
 
-public class QtWindow extends QtLayout implements QtSurfaceInterface {
+class QtWindow extends QtLayout implements QtSurfaceInterface {
     private final static String TAG = "QtWindow";
 
     private View m_surfaceContainer;