mx-takeover: refactor and disable on darwin (#408799)

pkgs/by-name/mx/mx-takeover/package.nix

@@ -1,5 +1,6 @@
 {
   lib,
+  stdenv,
   buildGoModule,
   fetchFromGitHub,
 }:
@@ -24,10 +25,11 @@ buildGoModule rec {
 
   meta = with lib; {
     description = "Tool to work with DNS MX records";
-    mainProgram = "mx-takeover";
     homepage = "https://github.com/musana/mx-takeover";
-    changelog = "https://github.com/musana/mx-takeover/releases/tag/v${version}";
+    changelog = "https://github.com/musana/mx-takeover/releases/tag/v${src.tag}";
     license = licenses.mit;
     maintainers = with maintainers; [ fab ];
+    mainProgram = "mx-takeover";
+    broken = stdenv.hostPlatform.isDarwin;
   };
 }