Nym Seddon

Much appreciation to @cuviper for their help/discussion about the impl on Zulip.

Tried moving SymCC in-tree in LLVM, and using the new pass manager. Running into a linking issue, but will keep experimenting. (Apologies for deleting previous comments, went overzealous with housekeeping)

The crash is ultimately somewhere around `liblmdb-sys/mdb/libraries/liblmdb/mdb.c:5116`, so can raise an issue upstream if that is better, referencing this issue.

Also have a use-case for `AES_CBC_HMAC_SHA256` in [olm-rs](https://github.com/musoke/olm-rs). If @akhilles is still MIA, or not working on this, I can begin work on it.

> https://docs.rs/arbitrary/0.4.7/arbitrary/trait.Arbitrary.html#impl-Arbitrary-for-(B%2C%20C%2C%20D%2C%20E%2C%20F%2C%20G%2C%20H%2C%20I%2C%20J%2C%20K%2C%20L%2C%20M%2C%20N%2C%20O%2C%20P%2C%20Q%2C%20R%2C%20S%2C%20T%2C%20U%2C%20V%2C%20W%2C%20X%2C%20Y%2C%20Z%2C%20A) > > :sob: That is intense... :sweat_smile: I'm new to the `Arbitrary` trait, too. Ran across it when refactoring fuzzer code. Apparently, [structure-aware fuzzing](https://rust-fuzz.github.io/book/cargo-fuzz/structure-aware-fuzzing.html) is the way to...