libbsd: fixup on darwin

This is my attempt to get libbsd workin on Darwin. It's kind of a mess
right now with patches. Most of it are ugly hacks but at least it builds!

pkgs/development/libraries/libbsd/default.nix

@@ -1,18 +1,33 @@
-{ stdenv, fetchurl }:
+{ stdenv, fetchFromGitHub, autoreconfHook }:
 
 stdenv.mkDerivation rec {
   name = "libbsd-${version}";
   version = "0.8.3";
 
-  src = fetchurl {
-    url = "http://libbsd.freedesktop.org/releases/${name}.tar.xz";
-    sha256 = "1a1l7afchlvvj2zfi7ajcg26bbkh5i98y2v5h9j5p1px9m7n6jwk";
+  nativeBuildInputs = [ autoreconfHook ];
+
+  preAutoreconf = "mkdir m4";
+
+  patchPhase = ''
+    substituteInPlace configure.ac \
+      --replace "m4_esyscmd([./get-version])" "${version}"
+    sed -i '38i#undef strlcpy' include/bsd/string.h
+    sed -i '38i#undef strlcat' include/bsd/string.h
+    substituteInPlace src/setproctitle.c \
+     --replace 'extern typeof(setproctitle_impl) setproctitle_stub __attribute__((weak, alias("setproctitle_impl")));' ""
+  '';
+
+  src = fetchFromGitHub {
+    owner = "JackieXie168";
+    repo = "libbsd";
+    rev = "macosx-${version}";
+    sha256 = "1g5h6d7i297m0hs2l0dxvsx6p0z96959pzgp75drbb7mkrf32p2z";
   };
 
   meta = with stdenv.lib; {
     description = "Common functions found on BSD systems";
     homepage = http://libbsd.freedesktop.org/;
     license = licenses.bsd3;
-    platforms = platforms.linux;
+    platforms = platforms.linux ++ platforms.darwin;
   };
 }