Build fix after setPreferredPaintEngine was removed

Change-Id: I286529e0e1917ee3c808eba7dad0957dd4d8194f
Reviewed-on: http://codereview.qt.nokia.com/3083
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

examples/painting/composition/main.cpp

@@ -50,9 +50,6 @@ int main(int argc, char **argv)
 {
  //   Q_INIT_RESOURCE(deform);
 
-#ifdef QT_OPENGL_SUPPORT
-    QGL::setPreferredPaintEngine(QPaintEngine::OpenGL);
-#endif
     QApplication app(argc, argv);
 
     CompositionWidget compWidget(0);

src/opengl/qgl.h

@@ -101,8 +101,6 @@ class QGLContextPrivate;
 // Namespace class:
 namespace QGL
 {
-    Q_OPENGL_EXPORT void setPreferredPaintEngine(QPaintEngine::Type engineType);
-
     enum FormatOption {
         DoubleBuffer            = 0x0001,
         DepthBuffer             = 0x0002,