Motivation for this change

Hopefully fixes #49092

The new tree is:

result
├── lib
│   └── cups
│       └── filter
│           └── rastertobrlaser
└── share
    └── cups
        └── drv
            └── brlaser.drv

without the strange $out dir.

@wagnerf42: can you check if this fixes you issue ?

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Fits CONTRIBUTING.md.