blender: do not build on x86_64-darwin

Blender (specifically the ghost window library) depends on "metal" on apple devices.
(For details see source/intern/ghost/intern/GHOST_System.cc line 416ff)
It will and cannot build without it. Metal support should be introduced by apple sdk 11_2 onward. Once this has been updated in nixpkgs, this derivation can be revised.

pkgs/applications/misc/blender/default.nix

@@ -385,7 +385,8 @@ stdenv.mkDerivation (finalAttrs: {
     license = with lib.licenses; [ gpl2Plus ] ++ lib.optional cudaSupport unfree;
     platforms = [
       "aarch64-linux"
-      "x86_64-darwin"
+      # the current apple sdk is too old (currently 11_0) and fails to build "metal" on x86_64-darwin
+      # "x86_64-darwin"
       "x86_64-linux"
       "aarch64-darwin"
     ];