lbreakout2: disable hanging darwin Hydra builds

https://hydra.nixos.org/job/nixpkgs/staging-next/lbreakout2.aarch64-darwin

pkgs/by-name/lb/lbreakout2/package.nix

@@ -45,5 +45,6 @@ stdenv.mkDerivation (finalAttrs: {
     mainProgram = "lbreakout2";
     maintainers = with lib.maintainers; [ AndersonTorres ciil ];
     platforms = lib.platforms.unix;
+    hydraPlatforms = lib.platforms.linux; # build hangs on both Darwin platforms, needs investigation
   };
 })