tty_notify_if_available
tty_notify_if_available(target, source, true);
tty_notify_if_available(source, target, true);
tty_notify_if_available(target, sourceCookie->tty, true);
tty_notify_if_available(fTarget, fSource, true);
tty_notify_if_available(fSource, fTarget, true);
tty_notify_if_available(fTarget, fSource, false);
tty_notify_if_available(fSource, fTarget, false);
tty_notify_if_available(fTTY, (otherTTY->open_count > 0 ? otherTTY : NULL),
static void tty_notify_if_available(struct tty* tty, struct tty* otherTTY,