Re: [AH6] Disable mutable bits after AH header

Unfortunately I broke ah6_input() in that patch.  Thanks to Miyazawa-san
for notifying me of the problem.

In that patch I removed the nh_offset parameter to ipv6_clear_mutable_options.
That broke ah6_input() because it relies on that variable to set the nexthdr.

The following patch fixes this by moving this work out to the caller
xfrm6_rcv() where the information is already available.  It also removes
an unnecessary call to ip6_find_1stfragopt() in xfrm6_rcv() since nhoffp
already points to the nexthdr preceding the current header.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@redhat.com>