fix for missing define on OpenGL ES2
fix for missing define on OpenGL ES2

for opengl ES2 return 2.0 for gl version major.minor

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