Sync OpenBSD patchset 1069:

Add notify hooks for various events, the functions are currently empty
stubs but will be filled in for control mode later. From George Nachman.

window.c

@@ -365,6 +365,7 @@ window_set_name(struct window *w, const char *new_name)
 	if (w->name != NULL)
 		xfree(w->name);
 	w->name = xstrdup(new_name);
+	notify_window_renamed(w);
 }
 
 void