This patch bumps the `crucible` submodule to bring in the changes from
GaloisInc/crucible#1096 and updates the code in `crucible-mir-comp` and
`crux-mir-comp` accordingly. Some highlights:

* All of the `crux-mir-comp` test cases now use `crux::test` instead of
  `crux_test`.
* All of the `crux-mir-comp` test cases now scrub out the values of crate hash
  disambiguators to make their output more stable.
* The overrides in `crux-mir-comp` no longer depend on the specific
  disambiguator values being used, which makes them work with the sometimes
  unpredictable hash values used for crate disambiguators.
* I have added a `tyToShape` case for `TyStr` to handle new kinds of static
  values that arise in the new Rust nightly (mostly coming from constant values
  in the `fmt` crate). The code for this case is nearly identical to that in the
  `TySlice` case.
* There are now static values of type `TyFnPtr` in the new Rust nightly (mostly
  coming from constant values in the `fmt` crate), so in order to handle them
  in `clobberGlobals`, I needed to add a `FnPtrShape` data constructor to
  `TypeShape`. This is mostly a quick hack, since I implemented all other
  functionality for `FnPtrShape` with calls to `error`. Nevertheless, that is
  enough to make all of the tests pass. We can always fill out the calls to
  `error` later if need be.