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/net/dccp/output.c b/net/dccp/output.c
index d17fc90..9bf195d 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -424,8 +424,8 @@
 	/* Build and checksum header */
 	dh = dccp_zeroed_hdr(skb, dccp_header_size);
 
-	dh->dccph_sport	= inet_rsk(req)->loc_port;
-	dh->dccph_dport	= inet_rsk(req)->rmt_port;
+	dh->dccph_sport	= inet_rsk(req)->ir_loc_port;
+	dh->dccph_dport	= inet_rsk(req)->ir_rmt_port;
 	dh->dccph_doff	= (dccp_header_size +
 			   DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
 	dh->dccph_type	= DCCP_PKT_RESPONSE;