ip: support RFC4191 router preference

This allows querying and setting the route preference. It's usually set from
the IPv6 Neighbor Discovery Router Advertisement messages.

Introduced in "ipv6: expose RFC4191 route preference via rtnetlink", enqueued
for Linux 4.1.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
3 files changed