Allow code to compile if libovr is missing
Allow code to compile if libovr is missing

runewake2/opengl-examples,runewake2/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples