[mutter] clutter: Remove unused flag CLUTTER_FEATURE_SWAP_THROTTLE

[Jonas Ådahl <jadahl src gnome org>]

commit 593e610415f08d15e614cfdc29955ef3b893abb5
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Fri Jul 31 15:46:14 2020 +0800

    clutter: Remove unused flag CLUTTER_FEATURE_SWAP_THROTTLE
    
    It's been unused ever since e415cc538a.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1390

 clutter/clutter/clutter-backend.c | 8 --------
 clutter/clutter/clutter-enums.h   | 2 --
 2 files changed, 10 deletions(-)
---
diff --git a/clutter/clutter/clutter-backend.c b/clutter/clutter/clutter-backend.c
index bb3c0f6ca5..14c2539aeb 100644
--- a/clutter/clutter/clutter-backend.c
+++ b/clutter/clutter/clutter-backend.c
@@ -422,14 +422,6 @@ clutter_backend_real_get_features (ClutterBackend *backend)
       flags |= CLUTTER_FEATURE_STAGE_STATIC;
     }
 
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_THROTTLE))
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers throttling");
-      flags |= CLUTTER_FEATURE_SWAP_THROTTLE;
-    }
-  else
-    CLUTTER_NOTE (BACKEND, "Cogl doesn't support swap buffers throttling");
-
   if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_BUFFERS_EVENT))
     {
       CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers complete events");
diff --git a/clutter/clutter/clutter-enums.h b/clutter/clutter/clutter-enums.h
index bbc759d385..009d6d671c 100644
--- a/clutter/clutter/clutter-enums.h
+++ b/clutter/clutter/clutter-enums.h
@@ -951,7 +951,6 @@ typedef enum
 
 /**
  * ClutterFeatureFlags:
- * @CLUTTER_FEATURE_SWAP_THROTTLE: Set if backend throttles buffer swaps.
  * @CLUTTER_FEATURE_STAGE_STATIC: Set if stage size if fixed (i.e framebuffer)
  * @CLUTTER_FEATURE_STAGE_CURSOR: Set if stage has a graphical cursor.
  * @CLUTTER_FEATURE_SHADERS_GLSL: Set if the backend supports GLSL shaders.
@@ -966,7 +965,6 @@ typedef enum
  */
 typedef enum
 {
-  CLUTTER_FEATURE_SWAP_THROTTLE          = (1 << 3),
   CLUTTER_FEATURE_STAGE_STATIC           = (1 << 6),
   CLUTTER_FEATURE_STAGE_CURSOR           = (1 << 8),
   CLUTTER_FEATURE_SHADERS_GLSL           = (1 << 9),