Revert "Revert "darwin 10.12 commits""

This reverts commit 8505e710e7.

pkgs/os-specific/darwin/apple-source-releases/libutil/default.nix

@@ -1,13 +1,33 @@
-{ stdenv, appleDerivation }:
+{ stdenv, lib, appleDerivation, xcbuildHook
+
+# headersOnly is true when building for libSystem
+, headersOnly ? false }:
 
-# all symbols are located in libSystem
 appleDerivation {
-  installPhase = ''
-    mkdir -p $out/include
-    cp *.h $out/include
+  nativeBuildInputs = lib.optional (!headersOnly) xcbuildHook;
+
+  prePatch = ''
+    substituteInPlace tzlink.c \
+      --replace '#include <xpc/xpc.h>' ""
   '';
 
-  meta = with stdenv.lib; {
+  xcbuildFlags = "-target util";
+
+  installPhase = ''
+    mkdir -p $out/include
+  '' + lib.optionalString headersOnly ''
+    cp *.h $out/include
+  '' + lib.optionalString (!headersOnly)''
+    mkdir -p $out/lib $out/include
+
+    cp Products/Release/*.dylib $out/lib
+    cp Products/Release/*.h $out/include
+
+    # TODO: figure out how to get this to be right the first time around
+    install_name_tool -id $out/lib/libutil.dylib $out/lib/libutil.dylib
+  '';
+
+  meta = with lib; {
     maintainers = with maintainers; [ copumpkin ];
     platforms   = platforms.darwin;
     license     = licenses.apsl20;