Use top-level cctools when available

cctools was updated and migrated to the `by-name` hierarchy in nixpkgs,
which moves it to the top-level. It is also being added to
`darwin-aliases.nix`, which will make the old name unavailable for use
in nixpkgs. This change preferentially uses the new name while falling
back to the old one for out-of-tree users.

Relevant nixpkgs PRs:
- NixOS/nixpkgs#307880
- NixOS/nixpkgs#328077

default.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ./nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages.nix {

lib/expressions/CompositionExpression.js

@@ -119,9 +119,13 @@ CompositionExpression.prototype.toNixAST = function() {
  }),
  thenExpr: new nijs.NixAttrReference({
  attrSetExpr: new nijs.NixExpression("pkgs"),
- refExpr: new nijs.NixAttrReference({
- attrSetExpr: new nijs.NixExpression("darwin"),
- refExpr: new nijs.NixExpression("cctools")
+ refExpr: new nijs.NixExpression("cctools"),
+ orExpr: new nijs.NixAttrReference({
+ attrSetExpr: new nijs.NixExpression("pkgs"),
+ refExpr: new nijs.NixAttrReference({
+ attrSetExpr: new nijs.NixExpression("darwin"),
+ refExpr: new nijs.NixExpression("cctools")
+ }),
  }),
  }),
  elseExpr: null

tests/default-v14.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages-v14.nix {

tests/default-v16.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages-v16.nix {

tests/grunt/default.nix

@@ -12,7 +12,7 @@ let
  nodeEnv = import ../../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages.nix {

tests/lockfile-v2/default.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ../../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages.nix {

tests/lockfile/default.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ../../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages.nix {

tests/scoped/default.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ../../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages.nix {

tests/versionless/default.nix

@@ -8,7 +8,7 @@ let
  nodeEnv = import ../../nix/node-env.nix {
  inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
  inherit pkgs nodejs;
- libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
+ libtool = if pkgs.stdenv.isDarwin then pkgs.cctools or pkgs.darwin.cctools else null;
  };
 in
 import ./node-packages.nix {