Fix try #2 at QSurface missing a virtual destructor

All virtual base classes with accessible destructor should declare
the destructor as virtual too.

Change-Id: I2b07c7e824612af072d7802095d958dca8cc34c8
Reviewed-on: http://codereview.qt.nokia.com/4274
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

src/gui/kernel/qwindow.cpp

@@ -101,6 +101,10 @@ QWindow::~QWindow()
     destroy();
 }
 
+QSurface::~QSurface()
+{
+}
+
 void QWindow::setSurfaceType(SurfaceType surfaceType)
 {
     Q_D(QWindow);

src/gui/kernel/qwindow.h

@@ -81,6 +81,8 @@ public:
         Window
     };
 
+    virtual ~QSurface();
+
     SurfaceType surfaceType() const { return m_type; }
 
     virtual QSurfaceFormat format() const = 0;