[NETNS][IPV6]: Add ipv6 structure for netns.

Like the ipv4 part, this patch adds an ipv6 structure in the net
structure to aggregate the different resources to make ipv6 per
namespace.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv6.h

@@ -0,0 +1,10 @@
+/*
+ * ipv6 in net namespaces
+ */
+
+#ifndef __NETNS_IPV6_H__
+#define __NETNS_IPV6_H__
+
+struct netns_ipv6 {
+};
+#endif