void silc_client_abort_key_agreement(SilcClient client,
                                         SilcClientConnection conn,
                                         SilcClientEntry client_entry);

    This function can be called to unbind the hostname and the port for
    the key agreement protocol. However, this function has effect only
    before the key agreement protocol has been performed. After it has
    been performed the library will automatically unbind the port. The
    `client_entry' is the client to which we sent the key agreement
    request.  The key agreement completion callback will be called
    with SILC_KEY_AGREEMENT_ABORTED status.