Make sure rules don't use global mutable state by accident.

[L-as]

We ideally want something like the opposite of make_checked, i.e. something that resets the global mutable state to an invalid value.

I have a feeling the internal state of Snarky can become invalid if you do run_checked (let* () = f in let* () = g () in ()) if g () makes use of the global mutable state. I might be wrong though.