glew1.8 debug build fix

Source/Plugins/Plugin_VideoOGL/Src/Render.cpp

@@ -68,6 +68,10 @@
 #include <wx/image.h>
 #endif
 
+// glew1.8 doesn't define KHR_debug
+#ifndef GL_DEBUG_OUTPUT
+#define GL_DEBUG_OUTPUT 0x92E0
+#endif
 
 
 void VideoConfig::UpdateProjectionHack()