commneted out vtkRegressionTestImage

Also added coment about why this is commented out and  question as to why is the
include here in the first place.

Examples/Charts/Cxx/GraphItem.cxx

@@ -27,7 +27,9 @@
 
 #include "vtkObjectFactory.h"
 
-#include "vtkRegressionTestImage.h"
+// NOTE: @hcwiley commented this out as its not being used, and causes builds
+// to fail with examples on but testing off. Why is this included?
+//#include "vtkRegressionTestImage.h"
 
 class GraphAnimate : public vtkCommand
 {