Deprecate gtk_window_set_wmclass

This function was already documented as "don't use", and it is
removed in GTK+ 4, so deprecate it properly.

gtk/gtkwindow.c

@@ -2406,6 +2406,7 @@ gtk_window_get_title (GtkWindow *window)
  * benefit of the session manager. Setting the role allows the window
  * manager to restore window positions when loading a saved session.
  *
+ * Deprecated: 3.22
  **/
 void
 gtk_window_set_wmclass (GtkWindow *window,

gtk/gtkwindow.h

@@ -150,7 +150,7 @@ void       gtk_window_set_title                (GtkWindow           *window,
 						const gchar         *title);
 GDK_AVAILABLE_IN_ALL
 const gchar * gtk_window_get_title             (GtkWindow           *window);
-GDK_AVAILABLE_IN_ALL
+GDK_DEPRECATED_IN_3_22
 void       gtk_window_set_wmclass              (GtkWindow           *window,
 						const gchar         *wmclass_name,
 						const gchar         *wmclass_class);