Move and restructure objconv a bit

pkgs/development/tools/misc/objconv/default.nix

···
+{ stdenv, fetchFromGitHub }:
+
+stdenv.mkDerivation {
+  name = "objconv-1.0";
+
+  src = fetchFromGitHub {
+    owner  = "vertis";
+    repo   = "objconv";
+    rev    = "01da9219e684360fd04011599805ee3e699bae96";
+    sha256 = "1by2bbrampwv0qy8vn4hhs49rykczyj7q8g373ym38da3c95bym2";
+  };
+
+  buildPhase = "c++ -o objconv -O2 src/*.cpp";
+
+  installPhase = "mkdir -p $out/bin && mv objconv $out/bin";
+}

pkgs/top-level/all-packages.nix

···
 
   obexftp = callPackage ../tools/bluetooth/obexftp { };
 
+  objconv = callPackage ../development/tools/misc/objconv {};
+
   obnam = callPackage ../tools/backup/obnam { };
 
   ocz-toolbox = callPackage ../os-specific/linux/ocz-toolbox { };
···
 
     cmdline_sdk   = cmdline.sdk;
     cmdline_tools = cmdline.tools;
+
+    apple_sdk = callPackage ../os-specific/darwin/apple-sdk {};
+
+    libobjc = apple-source-releases.objc4;
   };
 
   devicemapper = lvm2;