[ovs-dev] fix compilation on FreeBSD

[Ethan Jackson]

> If Ethan tells us his plan, then maybe we can just execute that
> instead of implementing for BSD.  Ceteris paribus, I agree that it's
> better to delete code than to add more of it!

My plan is basically to delete the route_table code entirely because
the features it implements aren't particularly useful, or could be
implemented outside of Open vSwitch quite easily.  I would considering
writing a patch which simply disables route_table in BSD, and makes
sure the rest of the code handles a missing implementation gracefully.
 You could alternatively simply implement it.  It's not that
difficult.

Ethan