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/xfrm.h b/include/net/xfrm.h
index 11c890a..f2c5ba2 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -882,6 +882,7 @@
 	u32 path_cookie;
 };
 
+#ifdef CONFIG_XFRM
 static inline void xfrm_dst_destroy(struct xfrm_dst *xdst)
 {
 	dst_release(xdst->route);
@@ -894,6 +895,7 @@
 	xdst->partner = NULL;
 #endif
 }
+#endif
 
 extern void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev);
 
@@ -1536,9 +1538,11 @@
 }
 #endif
 
+#ifdef CONFIG_XFRM
 static inline struct xfrm_state *xfrm_input_state(struct sk_buff *skb)
 {
 	return skb->sp->xvec[skb->sp->len - 1];
 }
+#endif
 
 #endif	/* _NET_XFRM_H */