ruff: only generate completions if program can be executed

[SFrijters]

Description of changes

Getting ahead of #289517 for cross builds.

Fixes

$ nix build .#pkgsCross.aarch64-multiplatform.ruff -L
[...]
ruff-aarch64-unknown-linux-gnu> /nix/store/l30525lnvzaiwqihqzspgrljmvjfx9j6-stdenv-linux/setup: line 114: /nix/store/4ws8s0ri2si18djfz9pps62pj208mihf-ruff-aarch64-unknown-linux-gnu-0.4.7/bin/ruff: cannot execute binary file: Exec format error
ruff-aarch64-unknown-linux-gnu> /nix/store/l30525lnvzaiwqihqzspgrljmvjfx9j6-stdenv-linux/setup: line 114: /nix/store/4ws8s0ri2si18djfz9pps62pj208mihf-ruff-aarch64-unknown-linux-gnu-0.4.7/bin/ruff: cannot execute binary file: Exec format error
ruff-aarch64-unknown-linux-gnu> /nix/store/l30525lnvzaiwqihqzspgrljmvjfx9j6-stdenv-linux/setup: line 114: /nix/store/4ws8s0ri2si18djfz9pps62pj208mihf-ruff-aarch64-unknown-linux-gnu-0.4.7/bin/ruff: cannot execute binary file: Exec format error

which will cause errors.

Things done

• 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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[SFrijters]

Rebased to fix merge conflicts.

[GaetanLepage]

Diff LGTM !

[GaetanLepage]

Result of nixpkgs-review pr 317572 run on aarch64-darwin 1

[GaetanLepage]

Result of nixpkgs-review pr 317572 run on x86_64-darwin 1

[GaetanLepage]

Result of nixpkgs-review pr 317572 run on aarch64-linux 1

[GaetanLepage]

Result of nixpkgs-review pr 317572 run on x86_64-linux 1