[DCCP]: Introduce dccp_ipv4_af_ops

And make the core DCCP code AF agnostic, just like TCP, now its time
to work on net/dccp/ipv6.c, we are close to the end!

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/input.c

@@ -329,7 +329,7 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk,
 		dccp_set_state(sk, DCCP_PARTOPEN);
 
 		/* Make sure socket is routed, for correct metrics. */
-		inet_sk_rebuild_header(sk);
+		icsk->icsk_af_ops->rebuild_header(sk);
 
 		if (!sock_flag(sk, SOCK_DEAD)) {
 			sk->sk_state_change(sk);
@@ -444,7 +444,8 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 	 */
 	if (sk->sk_state == DCCP_LISTEN) {
 		if (dh->dccph_type == DCCP_PKT_REQUEST) {
-			if (dccp_v4_conn_request(sk, skb) < 0)
+			if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
+								    skb) < 0)
 				return 1;
 
 			/* FIXME: do congestion control initialization */