ipv4: call __ip_options_echo() in cookie_v4_check()

commit 971f10eca186cab238c49da ("tcp: better TCP_SKB_CB layout to reduce cache line misses")
missed that cookie_v4_check() still calls ip_options_echo() which uses
IPCB(). It should use TCPCB() at TCP layer, so call __ip_options_echo()
instead.

Fixes: commit 971f10eca186cab238c49da ("tcp: better TCP_SKB_CB layout to reduce cache line misses")
Cc: Krzysztof Kolasa <[e-mail]>
Cc: Eric Dumazet <[e-mail]>
Reported-by: Krzysztof Kolasa <[e-mail]>
Tested-by: Krzysztof Kolasa <[e-mail]>
Signed-off-by: Cong Wang <[e-mail]>
Signed-off-by: Cong Wang <[e-mail]>
Signed-off-by: Eric Dumazet <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/syncookies.c

···
 		int opt_size = sizeof(struct ip_options_rcu) + opt->optlen;
 
 		ireq->opt = kmalloc(opt_size, GFP_ATOMIC);
-		if (ireq->opt != NULL && ip_options_echo(&ireq->opt->opt, skb)) {
+		if (ireq->opt != NULL && __ip_options_echo(&ireq->opt->opt, skb, opt)) {
 			kfree(ireq->opt);
 			ireq->opt = NULL;
 		}