Make kern.hostname and friends readable in capability mode

[allanjude]

Summary

This would make D7999 easier

[cem]

Related: D8000 :-)

rwatson's okay with kern.hostname. I don't know what the others are for so I wasn't sure enabling them was okay.

[jonathan]

I think that these are all fine to make readable, for the same reason that the hostname is ok: allowing information to "leak" in a way that enables more software to use Capsicum sandboxing is a net win. If we wanted to obscure the host UUID then we should also be hiding anything that could be used to identify the machine, which seems distinctly unhelpful in our overall goal of World Domination (tm).

[cem]

In that case, go ahead and commit this instead of my D8000, @allanjude .