ss: display interface name as zone index when needed

ss: display interface name as zone index when needed

This change enable the ss command to display the interface name as zone index
for local addresses when needed.

For this enhanced display *_diag stuff is needed.

It is based on a first version by Bernd Eckenfels.

example:
Netid  State   Recv-Q Send-Q                 Local Address:Port    Peer Address:Port
udp    UNCONN  0      0      fe80::20c:29ff:fe1f:7406%eth1:9999              :::*
udp    UNCONN  0      0                                 :::domain            :::*
tcp    LISTEN  0      3                                 :::domain            :::*
tcp    LISTEN  0      5      fe80::20c:29ff:fe1f:7410%eth2:99                :::*

Signed-off-by: Francois-Xavier Le Bail <fx.lebail@yahoo.com>