lix: disable tests on x86_64-darwin

[eilvelia]

Things done

Fixes #337036

lix build has been broken on x86_64-darwin since the update to lix 2.91: https://hydra.nixos.org/job/nixpkgs/trunk/lixVersions.latest.x86_64-darwin/all (this is apparently caused by enabled LTO).

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • 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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[lilyball]

We should not be disabling failing tests, that doesn't fix the problem it just ignores it.

[eilvelia]

I'm not sure what the usual practices in nixpkgs are, but my thinking was: (a) the failing tests look to be related to the test suite itself and not to the actual differences in behavior; (b) fixing that may take a long time, while it is beneficial to get the binaries into the nix cache; (c) it is kinda sad to disable LTO which appears to actually work fine. I guess disabling LTO is a safer option. I wanted to change this PR to disable LTO instead, but I see that you already opened #353576, thanks, and so I'm closing this.