ofp-actions: Avoid buffer overread in BUNDLE action decoding.

Reported-at: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=9052
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Justin Pettit <jpettit@ovn.org>
format_alg(int port, struct ds *s)
{
    switch(port) {
    case IPPORT_FTP:
        ds_put_format(s, "%salg=%sftp,", colors.param, colors.end);
        break;
    case IPPORT_TFTP:
        ds_put_format(s, "%salg=%stftp,", colors.param, colors.end);
        break;
    case 0:
        /* Don't print. */
        break;
    default:
        ds_put_format(s, "%salg=%s%d,", colors.param, colors.end, port);
        break;
    }
}

format_alg(int port, struct ds *s)
{
    switch(port) {
    case IPPORT_FTP:
        ds_put_format(s, "%salg=%sftp,", colors.param, colors.end);
        break;
    case IPPORT_TFTP:
        ds_put_format(s, "%salg=%stftp,", colors.param, colors.end);
        break;
    case 0:
        /* Don't print. */
        break;
    default:
        ds_put_format(s, "%salg=%s%d,", colors.param, colors.end, port);
        break;
    }
}
