parse_remote_port: error out on illegal port numbers better

    /* no CURLOPT_PORT given, extract the one from the URL */

    char *rest;

    unsigned long port;

    long port;

    port=strtoul(portptr+1, &rest, 10);  /* Port number must be decimal */

    port=strtol(portptr+1, &rest, 10);  /* Port number must be decimal */

    if(rest != (portptr+1) && *rest == '\0') {

      /* The colon really did have only digits after it,

       * so it is either a port number or a mistake */

      if(port > 0xffff) {   /* Single unix standard says port numbers are

                              * 16 bits long */

        failf(data, "Port number too large: %lu", port);

    if((port < 0) || (port > 0xffff)) {

      /* Single unix standard says port numbers are 16 bits long */

      failf(data, "Port number out of range");

      return CURLE_URL_MALFORMAT;

    }

    else if(rest != &portptr[1]) {

      *portptr = '\0'; /* cut off the name there */

      conn->remote_port = curlx_ultous(port);

    }

    else if(!port)

    else

      /* Browser behavior adaptation. If there's a colon with no digits after,

         just cut off the name there which makes us ignore the colon and just

         use the default port. Firefox and Chrome both do that. */