resolve: add error message when resolving using SIGALRM

    /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */

    return Curl_resolv(conn, hostname, port, entry);

  if(timeout < 1000)

  if(timeout < 1000) {

    /* The alarm() function only provides integer second resolution, so if

       we want to wait less than one second we must bail out already now. */

    failf(data,

        "remaining timeout of %ld too small to resolve via SIGALRM method",

        timeout);

    return CURLRESOLV_TIMEDOUT;

  }

  /* This allows us to time-out from the name resolver, as the timeout

     will generate a signal and we will siglongjmp() from that here.

     This technique has problems (see alarmfunc).