Added a nix expression for GNU ADNS. The version-specific files merely

forward the appropriate hash value to the generic driver found in
default.nix.

svn path=/nixpkgs/trunk/; revision=12153

pkgs/development/libraries/adns/default.nix

@@ -0,0 +1,24 @@
+{ stdenv, fetchurl, version, versionHash, static }:
+
+stdenv.mkDerivation
+{
+  name = "adns-${version}";
+  meta =
+  {
+    homepage = "http://www.chiark.greenend.org.uk/~ian/adns/";
+    description = "Asynchronous DNS Resolver Library";
+    license = "LGPL-v2";
+  };
+  src = fetchurl
+  {
+    url = "ftp://ftp.chiark.greenend.org.uk/users/ian/adns/adns-${version}.tar.gz";
+    sha256 = "${versionHash}";
+  };
+  configureFlags = if static then "--disable-dynamic" else "--enable-dynamic";
+  CPPFLAGS = "-DNDEBUG";
+  CFLAGS = "-O3";
+  doCheck = 1;
+
+  # adns doesn't understand the automatic --disable-shared from the Cygwin stdenv.
+  cygwinConfigureEnableShared = true;
+}