Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Very minor warns fix. Add a declaration for an unused parameter.

Add generalized power profile code.
This makes other power-management system (APM for now) to be able to
generate power profile change events (ie. AC-line status changes), and
other kernel components, not only the ACPI components, can be notified
the events.

- move subroutines in acpi_powerprofile.c (removed) to kern/subr_power.c
- call power_profile_set_state() also from APM driver when AC-line
status changes
- add call-back function for Crusoe LongRun controlling on power
profile changes for a example

Some fix for the recent apm module changes.
- Now that apm loadable module can inform its existence to other kernel
components (e.g. i386/isa/clock.c:startrtclock()'s TCS hack).
- Exchange priority of SI_SUB_CPU and SI_SUB_KLD for above purpose.
- Add simple arbitration mechanism for APM vs. ACPI. This prevents
the kernel enables both of them.
- Remove obsolete `#ifdef DEV_APM' related code.
- Add abstracted interface for Powermanagement operations. Public apm(4)
functions, such as apm_suspend(), should be replaced new interfaces.
Currently only power_pm_suspend (successor of apm_suspend) is implemented.

Reviewed by: peter, arch@ and audit@