[IPSEC]: Use dst->header_len when resizing on output

Currently we use x->props.header_len when resizing on output.
However, if we're resizing at all we might as well go the whole hog
and do it for the whole dst.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_output.c

@@ -19,7 +19,8 @@
 
 static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
 {
-	int nhead = x->props.header_len + LL_RESERVED_SPACE(skb->dst->dev)
+	struct dst_entry *dst = skb->dst;
+	int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
 		- skb_headroom(skb);
 
 	if (nhead > 0)