XQuartz: GL: Buildfix for recent GLX changes

dispatch.h was leftover from an earlier implementation and is no longer
needed, so remove it since including it causes a build failure due to
conflicts between GL/gl.h and OpenGL/gl.h

Signed-off-by: Jeremy Huddleston <jeremyhu@apple.com>
Reviewed-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

hw/xquartz/GL/indirect.c

@@ -48,9 +48,6 @@
 #include <glxserver.h>
 #include <glxutil.h>
 
-typedef unsigned long long GLuint64EXT;
-typedef long long GLint64EXT;
-#include <dispatch.h>
 #include <glapi.h>
 
 #include "x-hash.h"