netfilter: nf_nat: add protoff argument to packet mangling functions

For mangling IPv6 packets the protocol header offset needs to be known
by the NAT packet mangling functions. Add a so far unused protoff argument
and convert the conntrack and NAT helpers to use it in preparation of
IPv6 NAT.

Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/include/linux/netfilter/nf_conntrack_amanda.h b/include/linux/netfilter/nf_conntrack_amanda.h
index 0bb5a69..4b59a158 100644
--- a/include/linux/netfilter/nf_conntrack_amanda.h
+++ b/include/linux/netfilter/nf_conntrack_amanda.h
@@ -4,6 +4,7 @@
 
 extern unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
 					  enum ip_conntrack_info ctinfo,
+					  unsigned int protoff,
 					  unsigned int matchoff,
 					  unsigned int matchlen,
 					  struct nf_conntrack_expect *exp);