The base directory is now the machine bucket, which is everything that affects
codegen that you can ask FEX about offline: FEX compiler version, host features.
The DB files now carry a process bucket, which is everything else that can
affect codegen, on the user/process side: 32-bitness and config.
Both together are still the bucket hash that gets laced into every lookup key,
so we still won't load mismatching code because a file is in the wrong spot.