diffutils: disable tests on aarch64 musl

[alyssais]

Description of changes

The tests have never worked on aarch64 musl, so this restores the previous behaviour on that platform of building successfully even though the tests don't pass.

Since the tests work on x86_64 musl, and not aarch64 musl, my best guess having not looked too closely is that the difference is because aarch64 is stuck on ancient bootstrap tools for musl that cause all sorts of problems. Hopefully we can revert this once the bootstrap tools are updated. Having diffutils building is a prerequisite to doing that.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 23.11 Release Notes (or backporting 23.05 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.

[Artturin]

nix build --impure --expr "with import ./. { crossSystem = { config = \"x86_64-unknown-linux-musl\"; }; }; diffutils"
fails too

FAIL: test-getopt-gnu
=====================
test-getopt.h:659: assertion 'optind == 2' failed
FAIL test-getopt-gnu (exit status: 134)
FAIL: test-getopt-posix
=======================
test-getopt.h:659: assertion 'optind == 2' failed
FAIL test-getopt-posix (exit status: 134)
SKIP: test-mbrtowc1.sh
======================

pkgsMusl.diffutils builds

[alyssais]

I'm not sure what the best thing to do about x86_64 cross is — I think maybe I'd prefer to leave that and hope somebody actually tries to debug it at some point, because for that we don't have an excuse (of old bootstrap tools).

[yu-re-ka]

FYI pkgsMusl.patchutils_0_4_2 also has a problem. I don't know if it is related to either of the other two.

[alyssais]

I've changed this to check the build platform instead of the host platform, because I realised there'd be no need to disable the tests when building pkgsStatic.diffutils from glibc, or when cross compiling to glibc from musl (which doesn't currently work, but will with #259964).

We now have the musl stdenvBootstrapTools jobs on Hydra, so this is the last remaining blocker to having working aarch64-unknow-linux-musl builds.

I'll take this opportunity to restate that I want to keep this fix as narrowly scoped as possible, because in general, test failures should be investigated rather than hidden, but this is a special case because it's likely due to having outdated bootstrap tools, and is blocking having newer bootstrap tools.