Add linux

Created by: eroom1966

@ross144 @davidharrishmc Please review the fact that I have changed the default value of QEMU in config/buildroot/wally-config.vh This was necessary due to the 'hacks' that were put in for QEMU to work.

I have also done quite a lot of changes to the wally tracer, this was due to the fact that it was a bottleneck during execution. I used the profiler in order to find the slow code and optimize.