xfrm: Introduce LINUX_MIB_XFRMFWDHDRERROR

XFRMINHDRERROR counter is ambigous when validating forwarding
path. It makes it tricky to debug when you have both in and fwd
validation.

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 2c5d931..4368e7b 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2045,8 +2045,7 @@
 	int res;
 
 	if (xfrm_decode_session(skb, &fl, family) < 0) {
-		/* XXX: we should have something like FWDHDRERROR here. */
-		XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
+		XFRM_INC_STATS(net, LINUX_MIB_XFRMFWDHDRERROR);
 		return 0;
 	}