Revert changes to tystring

[limepoutine]

@thewilsonator This unblocks #22017.

@WalterBright I wonder if it is necessary to break type names into multiple modules depending on architecture. I think D's semantics also allow replacing all long/ulong with llong/ullong (thoroughly, not this hacky) in DWARF, but I don't know the situation of importC and the like. Nevermind, I think keeping D names is just fine.

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Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#22019"

[thewilsonator]

+ sudo apt-get update --quiet=2
E: Failed to fetch https://packagecloud.io/github/git-lfs/ubuntu/dists/focal/InRelease  403  Forbidden [IP: 3.171.102.38 443]
E: The repository 'https://packagecloud.io/github/git-lfs/ubuntu focal InRelease' is not signed.

What? I assume that is unrelated.

[thewilsonator]

Thanks!