octavePackages.ocl: mark as broken

pkgs/development/octave-modules/ocl/default.nix

···
 {
   buildOctavePackage,
-  stdenv,
   lib,
   fetchurl,
 }:
···
       Single-Instruction-Multiple-Data (SIMD) computations, selectively
       using available OpenCL hardware and drivers.
     '';
-    # error: structure has no member 'dir'
-    broken = stdenv.hostPlatform.isDarwin;
+    # https://savannah.gnu.org/bugs/?66964
+    broken = true;
   };
 }