Fix compilation error that occurs when compiling without the OVR library.
Fix compilation error that occurs when compiling without the OVR library.

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