[NETFILTER]: Remove IPv4 only connection tracking/NAT

Remove the obsolete IPv4 only connection tracking/NAT as scheduled in
feature-removal-schedule.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 0e690e3..1c6b8bd 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -250,6 +250,11 @@
 	return test_bit(IPS_DYING_BIT, &ct->status);
 }
 
+static inline int nf_ct_is_untracked(const struct sk_buff *skb)
+{
+	return (skb->nfct == &nf_conntrack_untracked.ct_general);
+}
+
 extern unsigned int nf_conntrack_htable_size;
 extern int nf_conntrack_checksum;
 extern atomic_t nf_conntrack_count;