netfilter: conntrack: align nf_conn on cacheline boundary

increases struct size by 32 bytes (288 -> 320), but it is the right thing,
else any attempt to (re-)arrange nf_conn members by cacheline won't work.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_core.c

@@ -1731,7 +1731,7 @@ int nf_conntrack_init_start(void)
 
 	nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
 						sizeof(struct nf_conn), 0,
-						SLAB_DESTROY_BY_RCU, NULL);
+						SLAB_DESTROY_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
 	if (!nf_conntrack_cachep)
 		goto err_cachep;