[mutter] cogl: Remove unneeded X11 includes from various headers

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit d5a70c7669ea3c0b11f36a6d6c16981627a59231
Author: Adam Jackson <ajax redhat com>
Date:   Tue Dec 17 10:41:44 2019 -0500

    cogl: Remove unneeded X11 includes from various headers
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/977

 cogl/cogl/cogl-framebuffer-private.h | 4 ----
 cogl/cogl/cogl-onscreen.c            | 4 ----
 cogl/cogl/cogl-renderer-private.h    | 4 ----
 3 files changed, 12 deletions(-)
---
diff --git a/cogl/cogl/cogl-framebuffer-private.h b/cogl/cogl/cogl-framebuffer-private.h
index 9700fb1d6..7bb02456d 100644
--- a/cogl/cogl/cogl-framebuffer-private.h
+++ b/cogl/cogl/cogl-framebuffer-private.h
@@ -41,10 +41,6 @@
 #include "cogl-gl-header.h"
 #include "cogl-clip-stack.h"
 
-#ifdef COGL_HAS_XLIB_SUPPORT
-#include <X11/Xlib.h>
-#endif
-
 typedef enum _CoglFramebufferType {
   COGL_FRAMEBUFFER_TYPE_ONSCREEN,
   COGL_FRAMEBUFFER_TYPE_OFFSCREEN
diff --git a/cogl/cogl/cogl-onscreen.c b/cogl/cogl/cogl-onscreen.c
index 2aab3950e..1bd1d5911 100644
--- a/cogl/cogl/cogl-onscreen.c
+++ b/cogl/cogl/cogl-onscreen.c
@@ -42,10 +42,6 @@
 #include "cogl-poll-private.h"
 #include "cogl-gtype-private.h"
 
-#ifdef COGL_HAS_X11_SUPPORT
-#include "cogl-xlib-renderer.h"
-#endif
-
 static void _cogl_onscreen_free (CoglOnscreen *onscreen);
 
 COGL_OBJECT_DEFINE_WITH_CODE_GTYPE (Onscreen, onscreen,
diff --git a/cogl/cogl/cogl-renderer-private.h b/cogl/cogl/cogl-renderer-private.h
index d79716d4f..66634c075 100644
--- a/cogl/cogl/cogl-renderer-private.h
+++ b/cogl/cogl/cogl-renderer-private.h
@@ -40,10 +40,6 @@
 #include "cogl-closure-list-private.h"
 #include "winsys/cogl-winsys-private.h"
 
-#ifdef COGL_HAS_XLIB_SUPPORT
-#include <X11/Xlib.h>
-#endif
-
 typedef const CoglWinsysVtable *(*CoglCustomWinsysVtableGetter) (CoglRenderer *renderer);
 
 struct _CoglRenderer