Write embedding zone using Reed-Solomon.

	Write embedding zone using Reed-Solomon.

	* Makefile.util.def (grub-setup): Add grub-core/lib/reed_solomon.c.
	* grub-core/Makefile.am (rs_decoder.S): New target.
	(kern/i386/pc/startup.S): Depend on rs_decoder.S.
	* grub-core/kern/i386/pc/startup.S (reed_solomon_redundancy): New field.
	(multiboot): Move to RS part.
	(post_reed_solomon): New label.
	(grub_boot_drive): Move to non-RS part since it's modified in memory
	on boot.
	Include rs_decoder.S.
	* grub-core/lib/reed_solomon.c: New file.
	* include/grub/offsets.h (GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY):
	New definition.
	(GRUB_KERNEL_I386_PC_MULTIBOOT_SIGNATURE): Removed.
	(GRUB_KERNEL_I386_PC_RAW_SIZE): Updated.
	(GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART): New definition.
	* include/grub/partition.h (grub_partition_map): Change prototype of
	embed to allow returning additional sectors.
	* include/grub/reed_solomon.h: New file.
	* util/grub-setup.c (setup): Handle Reed-Solomon.