qt6: broken on darwin

[wegank]

Steps To Reproduce

Steps to reproduce the behavior:

1. build qt6.qtbase

Build log

error: Package ‘mtdev-1.1.6’ in /Users/weijiawang/Projects/nixpkgs/pkgs/development/libraries/mtdev/default.nix:14 is not supported on ‘aarch64-darwin’, refusing to evaluate.

Additional context

The regression is due to #192057, which forgot to maintain the stdenv.isLinux guard on darwin. While it is straightforward to fix the aarch64-darwin build, it isn't enough for x86_64-darwin due to #210861.

Notify maintainers

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
output here