* grub-core/Makefile.core.def (halt): Add commands/acpihalt.c on i386-pc.
* grub-core/commands/acpihalt.c: New file.
* grub-core/commands/i386/pc/halt.c (grub_cmd_halt): Call grub_acpi_halt.
* include/grub/acpi.h (grub_acpi_fadt): New member pm1a.
(grub_acpi_halt): New proto.
(GRUB_ACPI_SLP_EN): New const.
(GRUB_ACPI_SLP_TYP_OFFSET): Likewise.
(GRUB_ACPI_OPCODE_*): New enum.
(GRUB_ACPI_EXTOPCODE_*): Likewise.
