zzz: Rewrite to use new power device

[obiwac]

Summary

Previous script called acpiconf(8) (or apm(8) if ACPI wasn't supported,
although this was anyway redundant because APMIO just uses ACPI now).

Since a new generic power management interface was introduced, this isn't
sufficient, as this would only work for ACPI systems and for ACPI S3 suspend
(so no way to select suspend-to-idle). Rewrite in C to take advantage of the
new power interface.

We may want to add a switch to manually override the kern.power.suspend sysctl,
which is otherwise what the power device uses to decide which suspend type to
switch to (suspend-to-idle or firmware suspend), but this will require us to
amend the power interface.

Sponsored by: The FreeBSD Foundation

Test Plan

Still need to test this on an ACPI machine. Expected behaviour on machines which support S3: just suspend to S3 when running zzz.

If someone with a machine that supports ACPI S3 could test this works that'd be great :)

[obiwac]

also, TODO, update manpage

usr.sbin/zzz/Makefile

3

probably don't want this to be in the acpi package! but I don't know what the most appropriate thing here is.

[obiwac]

usr.sbin/zzz/zzz.c

41–43

I don't know if it's worth adding fallback support to APCIIO or APMIO?

[obiwac]

rebase