darwin purity: ruby-2.1.6

pkgs/development/interpreters/ruby/ruby-2.1.6.nix

@@ -7,6 +7,7 @@
 , libyaml, yamlSupport ? true
 , libffi, fiddleSupport ? true
 , ruby_2_1_6, autoreconfHook, bison, useRailsExpress ? true
+, libiconv, libobjc, libunwind
 }:
 
 let
@@ -47,7 +48,8 @@ stdenv.mkDerivation rec {
     # support is not enabled, so add readline to the build inputs if curses
     # support is disabled (if it's enabled, we already have it) and we're
     # running on darwin
-    ++ (op (!cursesSupport && stdenv.isDarwin) readline);
+    ++ (op (!cursesSupport && stdenv.isDarwin) readline)
+    ++ (ops stdenv.isDarwin [ libiconv libobjc libunwind ]);
 
   enableParallelBuilding = true;