voicevox: init at 0.20.0

[TomaSajt]

Description of changes

Supersedes #287354

Homepage: https://voicevox.hiroshiba.jp
(I didn't put this homepage in the meta, since it's always 1 click away from the GitHub repo)

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Note: downloading the voicevox_core prebuilt binaries takes a while.
Also note: the program's language is Japanese, so it might be difficult to navigate the program if you don't speak it.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin (VM)
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[TomaSajt]

For the record, before I add free = false: the CI seems to run fine

I didn't wait out aarch64-darwin, but I assume it's gonna build fine.

[sarahec]

Result of nixpkgs-review pr 319403 run on aarch64-darwin 1

3 packages failed to build:

• voicevox-core
• voicevox-engine
• voicevox-engine.dist

[TomaSajt]

I pushed some small changes.

One of them was changing stdenv.is* to stdenv.hostPlatform.is*

The other change was using replaceVars instead of substituteAll.
This change made me realize that substituteAll wasn't actually substituting _7zz_path and was leaving it as @_7zz_path@. replaceVars actually worked, because its implementation is just a wrapper for substitute --replace-fail @key@ value.
I changed the variable name to be less confusing, now both methods should work.

[sarahec]

I don't see any vars in the patch, so you should be able to remove replaceVars and just use the patch path.