Use the canonical glext.h on MacOS X as well (#define NO_SDL_GLEXT if…

… you don't want this)

include/SDL_opengl.h

@@ -34,19 +34,19 @@ static char rcsid =
 #endif
 #include <windows.h>
 #endif
+#ifndef NO_SDL_GLEXT
+#define __glext_h_  /* Don't let gl.h include glext.h */
+#endif
 #if defined(__APPLE__) && defined(__MACH__)
 #include <OpenGL/gl.h>	/* Header File For The OpenGL Library */
 #include <OpenGL/glu.h>	/* Header File For The GLU Library */
 #else
-#ifndef NO_SDL_GLEXT
-#define __glext_h_  /* Don't let gl.h include glext.h */
-#endif
 #include <GL/gl.h>	/* Header File For The OpenGL Library */
 #include <GL/glu.h>	/* Header File For The GLU Library */
+#endif
 #ifndef NO_SDL_GLEXT
 #undef __glext_h_
 #endif
-#endif
 
 /* This file taken from "GLext.h" from the Jeff Molofee OpenGL tutorials.
    It is included here because glext.h is not available on some systems.