xmonad: fix binary name lookup on armv7l when cross-compiled

[sorki]

Description

This patch along with NixOS/nixpkgs#397767 allows pre-built xmonad running on armv7l target.

GHC converts armv7l and similar to just arm https://git.science.uu.nl/f100183/ghc/-/blob/8fa4bf9ab3f4ea4b208f4a43cc90857987e6d497/aclocal.m4#L1874 making hostPlatform.system point to xmonad-arm7l-linux instead of correct xmonad-arm-linux.

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all
  or nix build --reference-lock-file flake.lock ./tests#test-all using Flakes.

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

• If this PR adds a new module

  • Added myself as module maintainer. See example.

Maintainer CC

[khaneliman]

Does this need to wait for that? Or can this go in before it hits unstable?

[sorki]

Does this need to wait for that? Or can this go in before it hits unstable?

No need, the change is fairly unobtrusive. Without the nixpkgs patch you'll simply fail earlier at xmonad --recompile step.