Fix perl store bindings

[B4dM4n]

Motivation

Hydra currently fails to show the build dependencies of it's builds (NixOS/hydra#1401) with an error like this:

error: not an absolute path: 'Nix::Store=SCALAR(0x3f5338e8)'

The invalid path the error is referring to, is produced in the current Perl bindings itself.

Context

When #9863 converted the Nix::Store free functions into member functions, the implicit this argument was not accounted for when iterating over the variable number of arguments in some functions.

The following functions are affected:

• computeFSClosure
• topoSortPaths (this causes the hydra error)
• exportPaths

flake.nix reproducing the error:

{
  # Current rev of github:NixOS/nix/2.26-maintenance
  inputs.nix.url = "github:NixOS/nix/0d039d4abec82c7c7c2787edea7fd3c732965f82";

  inputs.nixpkgs.follows = "nix/nixpkgs";

  outputs = {
    self,
    nixpkgs,
    nix,
    ...
  }: {
    packages.x86_64-linux.default =
      nixpkgs.legacyPackages.x86_64-linux.writers.writePerlBin "example" {
        libraries = [nix.hydraJobs.perlBindings.x86_64-linux];
      } ''
        use Nix::Store;

        my $store = Nix::Store->new();

        $store->computeFSClosure(0,0);
        # error: not an absolute path: '0' at /nix/store/y1g5c8wz7s2fr29fliq06v161asj6npr-example/bin/example line 6.

        $store->topoSortPaths();
        # error: not an absolute path: 'Nix::Store=SCALAR(0x3eca46b0)' at /nix/store/7vxyv8kcv01dz0gjs9cys27frbqj5bir-example/bin/example line 9.

        $store->exportPaths(1);
        # error: not an absolute path: '1' at /nix/store/ras8ghkb0pff4zwp8jycg48p5y3qgfdq-example/bin/example line 12.
      '';
  };
}

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[Ericson2314]

@B4dM4n As the person that made the change introducing the bug, thank you!! Very nice work investigating this!