illumos gate

The Cascade Lake perfmon data has been available for a little bit now. This updates the general cpcgen data and makes some changes to the overall tooling so as to allow for different steppings of processors belonging to different sources.

To test this I booted up three different systems, an Ivy Bridge client part, a Haswell client part, and Skylake server. I ran cpustat -h before and after to see the set of counters that existed. There were minor changes on the haswell and skylake parts which mimics the corresponding changes to the JSON description. On Ivy Bridge however, there were no changes which matches our expectations because there was no change to its JSON description.