message: Clear out g.pRender on cleanup so further tests don't explode
  The x86 Conhost UTs were failing because--when run in a specific order
  (SearchTests, then SelectionInputTests)--PrepareGlobalScreenBuffer would
  attempt to enable painting on a renderer that was dead and gone and
  pushing up daisies.
diff: @@ -86,8 +86,9 @@ public:
  void CleanupGlobalRenderer()
  {
  - const Globals& g = Microsoft::Console::Interactivity::ServiceLocator::LocateGlobals();
  + Globals& g = Microsoft::Console::Interactivity::ServiceLocator::LocateGlobals();
  delete g.pRender;
  + g.pRender = nullptr;
  }
  void PrepareGlobalScreenBuffer(const short viewWidth = s_csWindowWidth,
  