tunneling: Capture inner mac header during encapsulation.

This patch adds inner mac header. This will be used in next patch
to find tunner header length. Header len is required to copy tunnel
header to each gso segment.
This patch does not change any functionality.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 0278c7f..31c6737 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -673,6 +673,7 @@
 	new->mac_header		= old->mac_header;
 	new->inner_transport_header = old->inner_transport_header;
 	new->inner_network_header = old->inner_network_header;
+	new->inner_mac_header = old->inner_mac_header;
 	skb_dst_copy(new, old);
 	new->rxhash		= old->rxhash;
 	new->ooo_okay		= old->ooo_okay;
@@ -876,6 +877,7 @@
 		skb->mac_header += off;
 	skb->inner_transport_header += off;
 	skb->inner_network_header += off;
+	skb->inner_mac_header += off;
 }
 
 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)