ICE for emebedded builds

Tom and I have put some effort into integrating Ice into OE so we can
support control port builds.

It will take a bit before I can get the updates needed into meta-oe, so
I have pushed a couple of branches for people to poke at. They will go
away once I can push the ice stuff into meta-sdr (which is bloacked by
ice going into meta-oe)

Anyway, have fun:

https://github.com/balister/meta-sdr/tree/zeroc-ice-work

Philip