wlist_add
wlist_add (&anfds[fd].head, (WL)w);
wlist_add (&signals [w->signum - 1].head, (WL)w);
wlist_add (&childs [w->pid & ((EV_PID_HASHSIZE) - 1)], (WL)w);
wlist_add (&fs_hash [w->wd & ((EV_INOTIFY_HASHSIZE) - 1)].head, (WL)w);