Don't use direct pkt access

pkt field in Packet needs to be accessed via macro. This
patch supress some direct access.

src/stream-tcp.c

@@ -4087,7 +4087,7 @@ void StreamTcpPseudoPacketSetupHeader(Packet *np, Packet *p)
 {
     /* Setup the IP header */
     if (PKT_IS_IPV4(p)) {
-        np->ip4h = (IPV4Hdr *)(np->pkt + (np->pktlen - IPV4_GET_IPLEN(p)));
+        np->ip4h = (IPV4Hdr *)(GET_PKT_DATA(np) + (GET_PKT_LEN(np) - IPV4_GET_IPLEN(p)));
         PSUEDO_PKT_SET_IPV4HDR(np->ip4h, p->ip4h);
 
         /* Similarly setup the TCP header with ports in opposite direction */
@@ -4101,7 +4101,7 @@ void StreamTcpPseudoPacketSetupHeader(Packet *np, Packet *p)
         SET_TCP_DST_PORT(np, &np->dp);
 
     } else if (PKT_IS_IPV6(p)) {
-        np->ip6h = (IPV6Hdr *)(np->pkt + (np->pktlen - IPV6_GET_PLEN(p) - IPV6_HEADER_LEN));
+        np->ip6h = (IPV6Hdr *)(GET_PKT_DATA(np) + (GET_PKT_LEN(np) - IPV6_GET_PLEN(p) - IPV6_HEADER_LEN));
         PSUEDO_PKT_SET_IPV6HDR(np->ip6h, p->ip6h);
 
         /* Similarly setup the TCP header with ports in opposite direction */