net: reduce structures when XFRM=n

ifdef out
* struct sk_buff::sp		(pointer)
* struct dst_entry::xfrm	(pointer)
* struct sock::sk_policy	(2 pointers)

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index ada50c0..d6b750a 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -229,7 +229,9 @@
 	} sk_backlog;
 	wait_queue_head_t	*sk_sleep;
 	struct dst_entry	*sk_dst_cache;
+#ifdef CONFIG_XFRM
 	struct xfrm_policy	*sk_policy[2];
+#endif
 	rwlock_t		sk_dst_lock;
 	atomic_t		sk_rmem_alloc;
 	atomic_t		sk_wmem_alloc;