Deprecate gdk_window_set_debug_updates

This is gone in GTK+ 4, so lets deprecate it.

gdk/gdkwindow.c

@@ -4794,7 +4794,8 @@ gdk_window_thaw_toplevel_updates (GdkWindow *window)
  * yourself, though you might want to use this function to enable
  * updates sometime after application startup time.
  *
- **/
+ * Deprecated: 3.22
+ */
 void
 gdk_window_set_debug_updates (gboolean setting)
 {

gdk/gdkwindow.h

@@ -1061,7 +1061,7 @@ void       gdk_window_process_updates     (GdkWindow    *window,
 					   gboolean      update_children);
 
 /* Enable/disable flicker, so you can tell if your code is inefficient. */
-GDK_AVAILABLE_IN_ALL
+GDK_DEPRECATED_IN_3_22
 void       gdk_window_set_debug_updates   (gboolean      setting);
 
 GDK_AVAILABLE_IN_ALL

gtk/gtkmain.c

@@ -736,8 +736,10 @@ do_post_parse_initialization (int    *argc,
       g_log_set_always_fatal (fatal_mask);
     }
 
+G_GNUC_BEGIN_IGNORE_DEPRECATIONS
   if (debug_flags[0].flags & GTK_DEBUG_UPDATES)
     gdk_window_set_debug_updates (TRUE);
+G_GNUC_END_IGNORE_DEPRECATIONS
 
   gtk_widget_set_default_direction (gtk_get_locale_direction ());