TCPFLAG_SACK
tcpflags : SACK { srv_conf->tcpflags |= TCPFLAG_SACK; }
if (srv_conf->tcpflags & (TCPFLAG_SACK|TCPFLAG_NSACK)) {
tcpflags : SACK { proto->tcpflags |= TCPFLAG_SACK; }
if (proto->tcpflags & (TCPFLAG_SACK|TCPFLAG_NSACK)) {