New routing table code (ART) enabled in -current

With this commit, mpi@ enabled the new ART routing table implementation, which paves way for more MP network stack improvements down the line.

On misc@, Martin wrote this:

I just enabled ART in -current, it will be the default routing table backend in the next snapshots.

The plan is to squash the possible regressions with this new routing table backend then when we're confident enough, take its route lookup out of the KERNEL_LOCK(). Yes, this is one of the big steps for our network SMP improvements.

In order to make progress, we need your help to make sure this new backend works well on your setup. So please, go download the next snapshot and report back.

If you encounter any routing table regression, please make sure that you cannot reproduce it with your old kernel and include the output of

# route -n show

for the 2 kernels as well as the dmesg in your report.

I know that simple dhclient(8) based setups work with ART, so please do not flood us too much. It's always great to know that things work, but it's also hard to keep focus ;)

Thank your very much for your support!

We hope you put this to the test on various strange networking devices to flesh out bugs as soon as possible.