Fixed HeaderTesting.py to work with VTK_DELETE_FUNCTION
Fixed HeaderTesting.py to work with VTK_DELETE_FUNCTION

Thanks to David Gobbi for help.

keithroe/vtkoptix,SimVascular/VTK,keithroe/vtkoptix,keithroe/vtkoptix,SimVascular/VTK,SimVascular/VTK,SimVascular/VTK,SimVascular/VTK,keithroe/vtkoptix,keithroe/vtkoptix,keithroe/vtkoptix,keithroe/vtkoptix,SimVascular/VTK,SimVascular/VTK,keithroe/vtkoptix,SimVascular/VTK