[SK_BUFF]: Introduce skb_transport_header(skb)

For the places where we need a pointer to the transport header, it is
still legal to touch skb->h.raw directly if just adding to,
subtracting from or setting it to another layer header.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ipcomp6.c b/net/ipv6/ipcomp6.c
index 4a65016..5555c98 100644
--- a/net/ipv6/ipcomp6.c
+++ b/net/ipv6/ipcomp6.c
@@ -143,7 +143,7 @@
 	/* compression */
 	plen = skb->len - hdr_len;
 	dlen = IPCOMP_SCRATCH_SIZE;
-	start = skb->h.raw;
+	start = skb_transport_header(skb);
 
 	cpu = get_cpu();
 	scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);