net: shrink struct sock and request_sock by 8 bytes

One 32bit hole is following skc_refcnt, use it.
skc_incoming_cpu can also be an union for request_sock rcv_wnd.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 2dbb113..4c0892b 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -382,10 +382,10 @@
 	}
 
 	/* Try to redo what tcp_v4_send_synack did. */
-	req->window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
+	req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
 
 	tcp_select_initial_window(tcp_full_space(sk), req->mss,
-				  &req->rcv_wnd, &req->window_clamp,
+				  &req->rsk_rcv_wnd, &req->rsk_window_clamp,
 				  ireq->wscale_ok, &rcv_wscale,
 				  dst_metric(&rt->dst, RTAX_INITRWND));