[XFRM]: Add XFRM_MODE_xxx for future use.

Transformation mode is used as either IPsec transport or tunnel.
It is required to add two more items, route optimization and inbound trigger
for Mobile IPv6.
Based on MIPL2 kernel patch.

This patch was also written by: Ville Nuorvala <vnuorval@tcs.hut.fi>

Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index 008e69d..9954297 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -265,7 +265,7 @@
 		goto error;
 	
 	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
-	if (x->props.mode)
+	if (x->props.mode == XFRM_MODE_TUNNEL)
 		x->props.header_len += sizeof(struct iphdr);
 	x->data = ahp;