This changes can reduce source code differences between Linux and ACPICA
upstream to help improving the release automation.

The side effect of applying this patch in Linux is:
1. Some ACPICA initialization/termination APIs are no longer exported in
   Linux, these include:
    acpi_load_tables
    acpi_initialize_subsystem
    acpi_enable_subsystem
    acpi_initialize_objects
    acpi_terminate
2. This patch does not affect the following APIs as they are currently not
   marked with ACPI_EXPORT_SYMBOL in Linux:
    acpi_reallocate_root_table
    acpi_initialize_tables
Such functions should not be exported as they are internal to ACPI
subsystem in Linux, and will only be invoked inside of ACPI subsystem's
initialization routines marked with __init and termination routines marked
with __exit.  While on other OSPMs, such functions may still need to be
exported.

Thus this patch adds the configurability for ACPICA, so that it leaves
OSPMs to determine if the __init/__exit marked functions should be exported
or not.  Lv Zheng.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>