[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/unix/af_unix.c b/net/unix/af_unix.c
index 6069716..aec8cf1 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1319,7 +1319,7 @@
 		unix_attach_fds(siocb->scm, skb);
 	unix_get_secdata(siocb->scm, skb);
 
-	skb->h.raw = skb->data;
+	skb_reset_transport_header(skb);
 	err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
 	if (err)
 		goto out_free;