Main: Viewport - disable clearBuffers if clearEveryFrame is off
Main: Viewport - disable clearBuffers if clearEveryFrame is off

fixes forwarding in Compositors

paroj/ogre,OGRECave/ogre,paroj/ogre,paroj/ogre,OGRECave/ogre,OGRECave/ogre,OGRECave/ogre,paroj/ogre,paroj/ogre,OGRECave/ogre