cachix: move to by-name, build without docs (#466253)

pkgs/by-name/ca/cachix/package.nix

@@ -0,0 +1,13 @@
+{
+  lib,
+  haskell,
+  haskellPackages,
+}:
+let
+  inherit (haskell.lib) compose;
+in
+lib.pipe haskellPackages.cachix [
+  compose.justStaticExecutables
+  (compose.overrideCabal { mainProgram = "cachix"; })
+  lib.getBin
+]

pkgs/top-level/all-packages.nix

@@ -6910,12 +6910,6 @@ with pkgs;
     c-blosc2
     ;
 
-  cachix = (lib.getBin haskellPackages.cachix).overrideAttrs (old: {
-    meta = (old.meta or { }) // {
-      mainProgram = old.meta.mainProgram or "cachix";
-    };
-  });
-
   niv = lib.getBin (haskell.lib.compose.justStaticExecutables haskellPackages.niv);
 
   ormolu = lib.getBin (haskell.lib.compose.justStaticExecutables haskellPackages.ormolu);