Fix duplicate assimp messages.
Fix duplicate assimp messages.

Duplicate messages were appearing in the log when multiple models are
loaded (for all but the first loaded model).

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