treewide: disable checks on darwin

Not working in these cases:

- dconf
- paho-mqtt
- perl-gtk2
- perl-TAPParserSourceHandlerpgTAP

pkgs/development/python-modules/paho-mqtt/default.nix

@@ -1,5 +1,5 @@
 { lib, buildPythonPackage, fetchFromGitHub, isPy3k
-, pytestrunner, pytest, mock }:
+, stdenv, pytestrunner, pytest, mock }:
 
 buildPythonPackage rec {
   pname = "paho-mqtt";
@@ -20,6 +20,8 @@ buildPythonPackage rec {
 
   checkInputs = [ pytestrunner pytest ] ++ lib.optional (!isPy3k) mock;
 
+  doCheck = !stdenv.isDarwin;
+
   meta = with lib; {
     homepage = https://eclipse.org/paho;
     description = "MQTT version 3.1.1 client class";