Consider handling Intel's Control-Flow Enforcement Technology

I am trying to get [`xv6`](https://github.com/mit-pdos/xv6-public) to run on `v86` (so that I can study its behavior in-depth), but I was (briefly) blocked on the fact that `gcc` generates [`CET`](https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf) instructions by default.

I was able to unblock myself (by forcing `gcc` to not generate those instructions using `-fcf-protection=none`, but it is still stuck for some other reasons I haven't figured out yet.