nixos/nginx: allow 'pipe' and 'pipe2' SystemCallFilters

[Izorkin]

Motivation for this change

There is a possibility that nginx is using these calls.

https://github.com/nginx/nginx/blob/master/src/os/unix/ngx_posix_init.c#L124
https://github.com/nginx/nginx/blob/master/src/event/ngx_event_pipe.c#L119

cc @mweinelt @Mic92

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.

[mweinelt]

https://github.com/nginx/nginx/blob/master/src/os/unix/ngx_posix_init.c#L124

That ist dead code, see L117

https://github.com/nginx/nginx/blob/master/src/event/ngx_event_pipe.c#L119

That is just a String, i dont see a Pipe syscall.

[Mic92]

I agree with @mweinelt, pipe is not used at the moment.

[stale]

I marked this as stale due to inactivity. → More info