[SK_BUFF]: Introduce skb_reset_transport_header(skb)

For the common, open coded 'skb->h.raw = skb->data' operation, so that we can
later turn skb->h.raw into a offset, reducing the size of struct sk_buff in
64bit land while possibly keeping it as a pointer on 32bit.

This one touches just the most simple cases:

skb->h.raw = skb->data;
skb->h.raw = {skb_push|[__]skb_pull}()

The next ones will handle the slightly more "complex" cases.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 1abc488..63c05be 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -500,7 +500,7 @@
 			 * before previous one went down. */
 			if (frag) {
 				frag->ip_summed = CHECKSUM_NONE;
-				frag->h.raw = frag->data;
+				skb_reset_transport_header(frag);
 				__skb_push(frag, hlen);
 				skb_reset_network_header(frag);
 				memcpy(skb_network_header(frag), iph, hlen);