opendkim: adopt, cleanup and fix opendkim-genkey

pkgs/development/libraries/opendkim/default.nix

···
-{stdenv, fetchurl, openssl, libmilter, libbsd}:
+{ stdenv, fetchurl, pkgconfig, libbsd, openssl, libmilter
+, perl, makeWrapper }:
 
 stdenv.mkDerivation rec {
   name = "opendkim-2.10.3";
···
     sha256 = "06v8bqhh604sz9rh5bvw278issrwjgc4h1wx2pz9a84lpxbvm823";
   };
 
-  configureFlags="--with-openssl=${openssl} --with-milter=${libmilter}";
+  configureFlags= [ "--with-milter=${libmilter}" ];
+
+  nativeBuildInputs = [ pkgconfig makeWrapper ];
+
+  buildInputs = [ libbsd openssl libmilter perl ];
 
-  buildInputs = [openssl libmilter libbsd];
-  
-  meta = {
+  postInstall = ''
+    wrapProgram $out/sbin/opendkim-genkey \
+      --prefix PATH : ${openssl}/bin
+  '';
+
+  meta = with stdenv.lib; {
     description = "C library for producing DKIM-aware applications and an open source milter for providing DKIM service";
-    homepage = http://opendkim.org/;
-    maintainers = [ ];
-    platforms = with stdenv.lib.platforms; all;
+    homepage = http://www.opendkim.org/;
+    maintainers = with maintainers; [ abbradar ];
+    license = licenses.bsd3;
+    platforms = platforms.unix;
   };
-
 }