sysctl hw add nphyscpu variable

[Dieter BSD]

> I think hw.nsocket would make more sense. Whoever does this should
> check to see if any other UNIX platforms have picked a suitable name.

There are other sockets besides cpu sockets, so it might be a good idea
to include something that says what kind of socket.  I was thinking
n_cpu_socket, which isn't perfect either, since there are other things
that can be plugged into cpu sockets.  FPGAs for one.  Is there a more
generic term for cpu socket?

>> Probable things will get complicated a bit if the system is a guest
>> under Xen or other hypervisor. But probable there the nphyscpu should
>> be NA ?
>
> The hypervisor is able to pass through a geometry, so this would still
> make sense there.

If you are running bochs on a non-x86 machine (Alpha, Sparc, ARM, ...),
you have a virtual cpu plugged into a virtual socket.