Sync ACPICA with Intel's version
20160212.
* ACPI specification 6.1 support.
* Ensure \_SB_._INI is executed before any _REG methods are executed.
* Reverted a change made in version
20151218 which enabled method
invocations to be targets of various ASL operators (SuperName and
Target grammar elements). Also, disallow this in iASL (flagged as
errors now) in preparation for ACPI 6.2.
* Completed full support for the ACPI 6.0 External() AML opcode.
* In iASL, implemented support for an optional cross-reference
output file.
For a more detailed list, please see sys/contrib/dev/acpica/changes.txt.