ipv6: tcp: fix TCLASS value in ACK messages sent from TIME_WAIT

commit 66b13d99d96a (ipv4: tcp: fix TOS value in ACK messages sent from
TIME_WAIT) fixed IPv4 only.

This part is for the IPv6 side, adding a tclass param to ip6_xmit()

We alias tw_tclass and tw_tos, if socket family is INET6.

[ if sockets is ipv4-mapped, only IP_TOS socket option is used to fill
TOS field, TCLASS is not taken into account ]

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index b74f761..17ee85c 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -271,7 +271,7 @@
 							 &ireq6->loc_addr,
 							 &ireq6->rmt_addr);
 		ipv6_addr_copy(&fl6.daddr, &ireq6->rmt_addr);
-		err = ip6_xmit(sk, skb, &fl6, opt);
+		err = ip6_xmit(sk, skb, &fl6, opt, np->tclass);
 		err = net_xmit_eval(err);
 	}
 
@@ -326,7 +326,7 @@
 	dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL, false);
 	if (!IS_ERR(dst)) {
 		skb_dst_set(skb, dst);
-		ip6_xmit(ctl_sk, skb, &fl6, NULL);
+		ip6_xmit(ctl_sk, skb, &fl6, NULL, 0);
 		DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
 		DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
 		return;