Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Don't mention 'device acpi' or loading ACPI as a kernel module since the
latter is not supported. This is also more consistent with manpages for
other vendor-specific drivers such as acpi_ibm(4) and acpi_sony(4).

Import the acpi_aibs(4) driver written by Constantine A. Murenin.
It has more features than acpi_aiboost(4) and it will eventually replace
acpi_aiboost(4).

Submitted by: Constantine A. Murenin <cnst at FreeBSD.org>
Reviewed by: freebsd-acpi, imp
MFC after: 1 month