[NETFILTER]: nf_nat: autoload IPv4 connection tracking

Without this patch, the generic L3 tracker would kick in
if nf_conntrack_ipv4 was not loaded before nf_nat, which
would lead to translation problems with ICMP errors.

NAT does not make sense without IPv4 connection tracking
anyway, so just add a call to need_ipv4_conntrack().

Signed-off-by: Jan Engelhardt <[e-mail]>
Signed-off-by: Patrick McHardy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/netfilter/nf_nat_core.c

···
 	size_t i;
 	int ret;
 
+	need_ipv4_conntrack();
+
 	ret = nf_ct_extend_register(&nat_extend);
 	if (ret < 0) {
 		printk(KERN_ERR "nf_nat_core: Unable to register extension\n");