Curl_is_resolved(): FD_ZERO the file descriptors before we call ares_fds().

  static const struct timeval tv={0,0};

  int count;

  struct SessionHandle *data = conn->data;

  int nfds = ares_fds(data->state.areschannel, &read_fds, &write_fds);

  int nfds;

  FD_ZERO(&read_fds);

  FD_ZERO(&write_fds);

  nfds = ares_fds(data->state.areschannel, &read_fds, &write_fds);

  count = select(nfds, &read_fds, &write_fds, NULL,

                 (struct timeval *)&tv);