This has the side effect of now building on darwin. Previously, the
vendored luajit would fail to build.

Motivation for this change

Want to build on darwin. Also using the nixpkgs luajit and openssl rather than the vendored copies included in wrk (the vendored luajit failed to compile on darwin).

Note I included luajit in the function arguments, rather than lua combined with a lua = luajit in the callPackage because this package will only work with luajit and not other implementations. Happy to change that if that's the wrong style.

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• 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/)
• Fits CONTRIBUTING.md.