This provides the basic functionality of the iproute2 `route get`
command. It allows you to query netlink for the route to a destination
IP.Net
While implementing I noticed that the `s.Receive()` function was hanging
after the netlink response was recieved, so I added an additional clause
to break from the loop and return the decoded message if the NLM_F_MULTI
flag is not set.
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>