xeus-cling: mark as broken on darwin (#393026)

pkgs/applications/editors/jupyter-kernels/xeus-cling/default.nix

···
 {
+  lib,
   callPackage,
   cling,
   fetchurl,
···
     passthru = (oldAttrs.passthru or { }) // {
       unwrapped = xeus-cling-unwrapped;
     };
+
+    meta.badPlatforms = [
+      # fatal error: 'stdlib.h' file not found
+      lib.systems.inspect.patterns.isDarwin
+    ];
   });
 
   mkKernelSpec = std: {