SilcBuffer
    silc_command_reply_payload_encode_vap(SilcCommand cmd,
                                          SilcStatus status,
                                          SilcStatus error,
                                          SilcUInt16 ident, SilcUInt32 argc,
                                          va_list ap);

    This is equivalent to the silc_command_reply_payload_encode_va except
    takes the va_list as argument.