lixPackageSets.nix-eval-jobs: add nix passthru attribute

nix-eval-jobs is intimately tied to a specific Nix/Lix release and the
Nix specific version includes a passthru attribute so downstream users
can easily refer to it.

Propagating the same pattern for the Lix version allows it to more
readily be used as a drop in replacement.

pkgs/tools/package-management/lix/common-nix-eval-jobs.nix

@@ -40,6 +40,14 @@ stdenv.mkDerivation {
   # point 'nix edit' and ofborg at the file that defines the attribute,
   # not this common file.
   pos = builtins.unsafeGetAttrPos "version" args;
+
+  # Since this package is intimately tied to a specific Nix release, we
+  # propagate the Nix used for building it to make it easier for users
+  # downstream to reference it.
+  passthru = {
+    nix = lix;
+  };
+
   meta = {
     description = "Hydra's builtin `hydra-eval-jobs` as a standalone tool";
     mainProgram = "nix-eval-jobs";