SIGPOLL
kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
if ((signum != SIGPOLL) && sig_specific_sicodes(signum))
rt_sigmask(SIGPOLL) | rt_sigmask(SIGSYS) | \
[SIGPOLL] = { NSIGPOLL, SIL_POLL },