inet: includes a sock_common in request_sock

TCP listener refactoring, part 5 :

We want to be able to insert request sockets (SYN_RECV) into main
ehash table instead of the per listener hash table to allow RCU
lookups and remove listener lock contention.

This patch includes the needed struct sock_common in front
of struct request_sock

This means there is no more inet6_request_sock IPv6 specific
structure.

Following inet_request_sock fields were renamed as they became
macros to reference fields from struct sock_common.
Prefix ir_ was chosen to avoid name collisions.

loc_port   -> ir_loc_port
loc_addr   -> ir_loc_addr
rmt_addr   -> ir_rmt_addr
rmt_port   -> ir_rmt_port
iif        -> ir_iif

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 39bbfa1..24a0616 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1109,8 +1109,8 @@
 	ireq->wscale_ok = rx_opt->wscale_ok;
 	ireq->acked = 0;
 	ireq->ecn_ok = 0;
-	ireq->rmt_port = tcp_hdr(skb)->source;
-	ireq->loc_port = tcp_hdr(skb)->dest;
+	ireq->ir_rmt_port = tcp_hdr(skb)->source;
+	ireq->ir_loc_port = tcp_hdr(skb)->dest;
 }
 
 void tcp_enter_memory_pressure(struct sock *sk);