OSPMs like Linux trend to include all header files but leave empty stub
macros for a feature that is not configured during build.

This patch cleans up global variables that are defined in utglobal.c using
ACPI_INIT_GLOBAL mechanism.  In Linux, such global variables are used by
the subsystems external to ACPICA.
This patch also cleans up global variables that are defined in utglobal.c
using ACPI_GLOBAL mechanism.  In Linux, such global variables are not used
or should not be used by the subsystems external to ACPICA.

External global variables can be redefined by OSPMs using
ACPI_INIT_GLOBAL/ACPI_GLOBAL macros.  Thus the ACPI_GLOBAL/ACPI_INIT_GLOBAL
mechanisms can be used by OSPM to implement stubs for such external
globals.

This patch doesn't include code for Linux to use this new mechanism, thus
no functional changes.  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>