Adding setfib support to rc.d/routing

[Attila Nagy]

Hi,

Having multiple routing tables is a very nice and (was a) long awaited 
capability in FreeBSD. Having it since years is even more cool, because 
we can assume it's stable now.
But not having infrastructure support for it sucks, this makes people 
hacking with rc.local or various scripts in various places.

There is a(t least one) PR about it: conf/145440, which proposes a 
standard method for setting up different FIBs in a seems to be logical 
way, which is compatible with the current single routing table method of 
static_routes.

Are there any objections about this PR? Is there something we can do to 
get it committed?

Thanks,