net: export peernet2id_alloc

It will be used by openvswitch.
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/net_namespace.c

@@ -234,6 +234,7 @@ int peernet2id_alloc(struct net *net, struct net *peer)
 		rtnl_net_notifyid(net, RTM_NEWNSID, id);
 	return id;
 }
+EXPORT_SYMBOL_GPL(peernet2id_alloc);
 
 /* This function returns, if assigned, the id of a peer netns. */
 int peernet2id(struct net *net, struct net *peer)