Add a acpicall(8) utility for debugging and tweaking purposes.

Add a acpicall(8) utility for debugging and tweaking purposes.

It is based on ports' sysutils/acpi_call (from Maxim Ignatenko) with
a few changes by me:

* Rename acpi_call -> acpicall.

* Ioctl handling is in the main acpi.ko module.

* To enable it, the debug.acpi.allow_method_calls tunable needs to
  be set.

* In acpi_call, the mandatory -p option was used to pass the method's
  namespace path. I removed the option and made the path acpicall(8)'s
  argument.

* Wrote a manual page and cleaned up a bit.

The separate acpiio_mcall.h file was added because ACPIIO_DO_MCALL's
argument struct uses ACPICA types, so it needs acpi.h which acpiio.h
(a public header used by some ports) so far didn't need. So to avoid
any hassle, I put the ACPIIO_DO_MCALL ioctl into a separate header
(it's only used by acpicall(8) anyway).

The changes to kdump(1) and truss(1) are to include and build with
acpi.h.

Tested-by: tollens