GRUB_ACPI_OPCODE_STRING_CONST, GRUB_ACPI_OPCODE_BUFFER,
GRUB_ACPI_OPCODE_CREATE_WORD_FIELD
and GRUB_ACPI_OPCODE_CREATE_BYTE_FIELD.
* grub-core/commands/acpihalt.c [GRUB_DSDT_TEST]: Replace include of
i18n with gettext no-op.
(skip_data_ref_object): Support GRUB_ACPI_OPCODE_BUFFER and
GRUB_ACPI_OPCODE_STRING_CONST.
(get_sleep_type): Support GRUB_ACPI_OPCODE_CREATE_WORD_FIELD and
GRUB_ACPI_OPCODE_CREATE_BYTE_FIELD. Add handling of unknown opcodes.