I know we discussed moving the grsec overrider to the module, but I'm having second thoughts about this decision.

Nix provides one of the easiest ways of customizing and building your own kernel that I've ever seen. And the way we had before, it was easy to build (and customize) a grsec kernel using Nix on a non-NixOS distro. But if we move this code to the NixOS module, it won't be so easy anymore, the user will have to duplicate this code somewhere else and maintain it up-to-date with the grsecurity module.

Since this doesn't actually simplify much (it's only a matter of location), perhaps we could leave the overrider (and overriden kernels) in place, similar to how it was before?