Make surface and window accessible to subclasses

We need to access these in the Android plugin.

Change-Id: I8c7f279bbe0b7087260cceb1f965c833c0097984
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

src/plugins/platforms/eglfs/qeglfswindow.h

@@ -68,10 +68,12 @@ public:
     virtual void invalidateSurface();
     virtual void resetSurface();
 
-private:
-    WId m_winid;
+protected:
     EGLSurface m_surface;
     EGLNativeWindowType m_window;
+
+private:
+    WId m_winid;
     EGLConfig m_config;
     QSurfaceFormat m_format;
 };