[SIT]: Allow for IPPROTO_IPV6 protocol in namespaces.

This makes sit-generated traffic enter the namespace.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tunnel4.c

@@ -144,6 +144,7 @@ static struct net_protocol tunnel64_protocol = {
 	.handler	=	tunnel64_rcv,
 	.err_handler	=	tunnel64_err,
 	.no_policy	=	1,
+	.netns_ok	=	1,
 };
 #endif