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.

--HG--
branch : v1-9

jhu-lcsr-forks/ogre,jhu-lcsr-forks/ogre,jhu-lcsr-forks/ogre,jhu-lcsr-forks/ogre,jhu-lcsr-forks/ogre