[mutter] cogl/clip-stack-gl: Remove unused code: #define GL_CLIP_PLANEn

[Marge Bot <marge-bot src gnome org>]

commit f390340da5d662070b8ec7dd17d7a3d5c8bd715b
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Thu May 20 17:11:05 2021 +0800

    cogl/clip-stack-gl: Remove unused code: #define GL_CLIP_PLANEn
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1873>

 cogl/cogl/driver/gl/cogl-clip-stack-gl.c | 9 ---------
 1 file changed, 9 deletions(-)
---
diff --git a/cogl/cogl/driver/gl/cogl-clip-stack-gl.c b/cogl/cogl/driver/gl/cogl-clip-stack-gl.c
index 11a353f396..4975f34cf6 100644
--- a/cogl/cogl/driver/gl/cogl-clip-stack-gl.c
+++ b/cogl/cogl/driver/gl/cogl-clip-stack-gl.c
@@ -42,15 +42,6 @@
 #include "driver/gl/cogl-pipeline-opengl-private.h"
 #include "driver/gl/cogl-clip-stack-gl-private.h"
 
-#ifndef GL_CLIP_PLANE0
-#define GL_CLIP_PLANE0 0x3000
-#define GL_CLIP_PLANE1 0x3001
-#define GL_CLIP_PLANE2 0x3002
-#define GL_CLIP_PLANE3 0x3003
-#define GL_CLIP_PLANE4 0x3004
-#define GL_CLIP_PLANE5 0x3005
-#endif
-
 static void
 add_stencil_clip_rectangle (CoglFramebuffer *framebuffer,
                             CoglMatrixEntry *modelview_entry,