lixPackageSets.stable.nix-direnv: init

This adds nix-direnv to the lixPackageSets scope whose
fallback logic for finding a Nix implementation will use Lix

pkgs/tools/package-management/lix/default.nix

@@ -12,6 +12,7 @@
   ncurses,
   stdenv,
   clangStdenv,
+  nix-direnv,
   nix-fast-build,
 
   storeDir ? "/nix/store",
@@ -83,6 +84,10 @@ let
           stdenv = lixStdenv;
         };
 
+        nix-direnv = nix-direnv.override {
+          nix = self.lix;
+        };
+
         nix-eval-jobs = self.callPackage (callPackage ./common-nix-eval-jobs.nix nix-eval-jobs-args) {
           stdenv = lixStdenv;
         };