ip: ipv6: add tokenized interface identifier support

This patch adds support for tokenized IIDs, that enable
administrators to assign well-known host-part addresses
to nodes whilst still obtaining global network prefix
from Router Advertisements. This is the iproute2 part for
the kernel patch f53adae4eae5 (``net: ipv6: add tokenized
interface identifier support'').

Example commands with iproute2:

Setting a device token:
  # ip token set ::1a:2b:3c:4d/64 dev eth1

Getting a device token:
  # ip token get dev eth1
  token ::1a:2b:3c:4d dev eth1

Listing all tokens:
  # ip token list  (or: ip token)
  token :: dev eth0
  token ::1a:2b:3c:4d dev eth1

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
diff --git a/ip/ip.c b/ip/ip.c
index e10ddb2..69bd5ff 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -45,7 +45,7 @@
 "       ip [ -force ] -batch filename\n"
 "where  OBJECT := { link | addr | addrlabel | route | rule | neigh | ntable |\n"
 "                   tunnel | tuntap | maddr | mroute | mrule | monitor | xfrm |\n"
-"                   netns | l2tp | tcp_metrics }\n"
+"                   netns | l2tp | tcp_metrics | token }\n"
 "       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |\n"
 "                    -f[amily] { inet | inet6 | ipx | dnet | bridge | link } |\n"
 "                    -4 | -6 | -I | -D | -B | -0 |\n"
@@ -80,6 +80,7 @@
 	{ "tunl",	do_iptunnel },
 	{ "tuntap",	do_iptuntap },
 	{ "tap",	do_iptuntap },
+	{ "token",	do_iptoken },
 	{ "tcpmetrics",	do_tcp_metrics },
 	{ "tcp_metrics",do_tcp_metrics },
 	{ "monitor",	do_ipmonitor },