Unix: Substituted select -> poll also in congestion checker

int

sk_rx_ready(sock *s)

{

  fd_set rd, wr;

  struct timeval timo;

  int rv;

  FD_ZERO(&rd);

  FD_ZERO(&wr);

  FD_SET(s->fd, &rd);

  timo.tv_sec = 0;

  timo.tv_usec = 0;

  struct pollfd pfd = { .fd = s->fd };

  pfd.events |= POLLIN;

 redo:

  rv = select(s->fd+1, &rd, &wr, NULL, &timo);

  rv = poll(&pfd, 1, 0);

  if ((rv < 0) && (errno == EINTR || errno == EAGAIN))

    goto redo;