util-linux: use systemdLibs, minor cleanup

[drupol]

I was investigating why systemd was required in a Home Manager profile when I found out that util-linux was requiring it.

This PR is a proposal, similar to #433641

Feel free to let me know what you think.

Here's the closure size after/before:

❯ nix path-info -Sh ./result-bin
/nix/store/qx5wjl2d6bpy82vwkvv9hfm3nfbsm44r-util-linux-2.41.1-bin         88.1 MiB
❯ jj new master
❯ nix-build -A util-linux
/nix/store/ad5skbqn01fbmgwd0b879zy5x5skgxj1-util-linux-2.41.1-bin
❯ nix path-info -Sh ./result-bin
/nix/store/ad5skbqn01fbmgwd0b879zy5x5skgxj1-util-linux-2.41.1-bin        206.7 MiB

On top of that, this PR make a very minor cleanup in the postInstall attribute, regrouping lines that are meant to be together, making it easier to read.

Lastly, it also fixes the use of the finalAttrs pattern, there's no need to use rec when using it.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

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[vog]

All 3 commits look fine to me!

[vog]

@drupol The changes themselves are fine! However:

1. Please rebase your PR on the "staging" branch, because of the many rebuilds it triggers (see also php: fix systemdLibs dependency #433641).
2. Please update your PR description to clarify that this PR also performs some code cleanup in addition to the actual change to systemdLibs (which are all fine, but should be mentioned early on)
3. Please tick the appropriate check boxes in "Things done", e.g. whether you have successfully built it on the
   x86_64-linux platform.

[vog]

Looks all very good to me! 👍

[numinit]

This is a good change! One thing consumers can always do is depend on util-linuxMinimal if you don't want systemd or other "bloat" at all.

[LordGrimmauld]

Btw if you are interested in reducing the reverse closure of util-linux: The currently biggest consumers are qt6 qtbase, xvfb-run and polkit, everything else is less than 1k reverse dependencies. You might want to look into whether those can use minimal util-linux. I do expect polkit would want systemd/pam though.

[numinit]

Looks good, I can still build up to util-linux.