clutter/stage: Remove clutter_stage_new()

It's never expected that anything creates its own stage directly, so
remove the constructor function.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1364

clutter/clutter/clutter-stage.c

@@ -2591,29 +2591,6 @@ G_DEFINE_BOXED_TYPE (ClutterPerspective, clutter_perspective,
                      clutter_perspective_copy,
                      clutter_perspective_free);
 
-/**
- * clutter_stage_new:
- *
- * Creates a new, non-default stage. A non-default stage is a new
- * top-level actor which can be used as another container.
- *
- * The ability to support multiple stages depends on the current
- * backend. Use clutter_feature_available() and
- * %CLUTTER_FEATURE_STAGE_MULTIPLE to check at runtime whether a
- * backend supports multiple stages.
- *
- * Return value: a new stage, or %NULL if the default backend does
- *   not support multiple stages. Use clutter_actor_destroy() to
- *   programmatically close the returned stage.
- *
- * Since: 0.8
- */
-ClutterActor *
-clutter_stage_new (void)
-{
-  return g_object_new (CLUTTER_TYPE_STAGE, NULL);
-}
-
 /**
  * clutter_stage_ensure_viewport:
  * @stage: a #ClutterStage

clutter/clutter/clutter-stage.h

@@ -132,9 +132,6 @@ GType clutter_perspective_get_type (void) G_GNUC_CONST;
 CLUTTER_EXPORT
 GType clutter_stage_get_type (void) G_GNUC_CONST;
 
-CLUTTER_EXPORT
-ClutterActor *  clutter_stage_new                               (void);
-
 CLUTTER_EXPORT
 void            clutter_stage_get_perspective                   (ClutterStage          *stage,
 			                                         ClutterPerspective    *perspective);