Fix RTSS bug in visual tests. * Old code attempted to use RTSS to generate shader for   empty null sample at end of testing.  Now this case is   skipped.
Fix RTSS bug in visual tests.
* Old code attempted to use RTSS to generate shader for
  empty null sample at end of testing.  Now this case is
  skipped.

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