netbsd.sys: fix build

[alyssais]

Motivation for this change

Tested with

nix-build -A pkgsCross.x86_64-netbsd.netbsd.sys

I haven't tested what happens if I try to build it on Linux without going through pkgsCross.

Note that despite the comment above the package definition, this is not the full NetBSD kernel, only the headers, firmware and bootloader. I would like it to also build the kernel, but haven't managed to get that working yet (but I'm probably close).

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• 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 nixpkgs-review --run "nixpkgs-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)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[sternenseemann]

Native compilation on x86_64-linux fails:

In file included from /nix/store/m82xc9v1h6p06vhvva2gbl69mjsdvddm-glibc-2.32-40-dev/include/features.h:489,
                 from /nix/store/g9iwhx99jvwv3mh9fr5l7jv1ad4qpnha-compat-netbsd-8.0/include/compat_defs.h:27,
                 from /nix/store/g9iwhx99jvwv3mh9fr5l7jv1ad4qpnha-compat-netbsd-8.0/include/nbtool_config.h:875,
                 from <command-line>:
/nix/store/m82xc9v1h6p06vhvva2gbl69mjsdvddm-glibc-2.32-40-dev/include/gnu/stubs.h:7:11: fatal error: gnu/stubs-32.h: No such file or directory
    7 | # include <gnu/stubs-32.h>
      |           ^~~~~~~~~~~~~~~~
compilation terminated.
*** [mbr.o] Error code 1

[alyssais]

Native compilation on x86_64-linux fails

I think that's fine. This package should probably be NetBSD-only, but the meta.platforms line is commented out for some reason. I'd like to leave it that way for now until I have a better handle on why that might have been.

Sound okay to you?

[sternenseemann]

Sound okay to you?

Sure, don't see why we necessarily need the NetBSD kernel on Linux…

FWIW, pkgsCross.x86_64-netbsd.netbsd.sys builds for me as well. pkgsCross.x86_64-netbsd-llvm.netbsd.sys chokes on csu, something we should tackle somewhere else (if feasible).

uudecode also compiles with the native linux stdenv.

No real comments from my side.

[alyssais]

Yeah, I've changed my mind and added the meta.platforms line.