In preparation for partial modularization of the acpi(4) subtree.

* * *

XXX: The internal memory tracking of ACPICA, available when
ACPI_DBG_TRACK_ALLOCATIONS is defined, has been removed
from ACPI_DEBUG.

This is due to the instability of the ABI of ACPICA.

If the memory tracking is enabled, ACPICA will insert a header
to each memory allocation. As a consequence, when ACPI specific
code is loaded as a kernel module and the running kernel has
been compiled with ACPI_DEBUG, the result is an instant panic.
This happens because of unaligned memory access when the code
tries to use ACPI_FREE for a buffer obtained via ACPI_ALLOCATE,
AcpiEvaluateObject(), and related calls.

If the involved memory statistics are required, a separate constant
ACPI_DEBUG_ALLOC is available in options(4) for ACPI_DEBUG kernels.

* * *

Discussed with, and ok'ed by, jmcneill@ and pooka@.

(jruoho)