pkgsStatic.libselinux: fix build

[alyssais]

Motivation for this change

@SCOTT-HAMILTON I figured it's time to start posting some of the static work I've been doing in the last few months, to avoid any more duplication of effort. There are a few areas where our work has overlapped, but it looks like our end goals are very different (I've basically given up for GUI stuff), so hopefully there shouldn't be too many of these things where we've both come up with ways of doing the same thing. This is similar to your approach in #136107, except that it uses a patch that is suitable for upstream (and will hopefully be accepted soon), and the patch works for non-static builds too (it just provides a knob that allows shared libraries to be disabled). I think this is better because it means we're not building from slightly different sources when doing static builds (which hopefully means the patch won't stop applying next time selinux is updated if whoever does it doesn't test static builds), and if my patch is accepted upstream, we won't need to keep this patch around forever. I'd really appreciate your review.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 21.11 Release Notes (or backporting 21.05 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
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[SCOTT-HAMILTON]

LGTM, my patch wasn't meant to be applied upstream so definitly would prefer yours.

[alyssais]

@ofborg eval

[alyssais]

@ofborg build pkgsStatic.libselinux libselinux