fix typo in dgr.c
fix typo in dgr.c

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