Support xz compression on yeeloong.

	Support xz compression on yeeloong.

	* Makefile.util.def (grub-mkimage): Add $(LIBLZMA).
	* configure.ac: Check for LZMA.
	* grub-core/Makefile.core.def (xz_decompress): New target.
	(none_decompress): Likewise.
	* grub-core/boot/decompressor/minilib.c: New file.
	* grub-core/boot/decompressor/none.c: Likewise.
	* grub-core/boot/decompressor/xz.c: Likewise.
	* grub-core/kern/mips/cache.S: Change to noreorder nomacro.
	* grub-core/kern/mips/cache_flush.S: Likewise.
	* grub-core/kern/i386/pc/lzma_decode.S: Remove dead code.
	* grub-core/kern/mips/startup.S: Move first stage to ...
	* grub-core/boot/mips/startup_raw.S: ...here. Change to noreorder
	nomacro.
	* grub-core/kern/mips/startup.S: Change to noreorder nomacro.
	* grub-core/lib/mips/relocator_asm.S: Change to noreorder nomacro.
	* grub-core/lib/xzembed/xz_dec_bcj.c [GRUB_EMBED_DECOMPRESSOR]:
	Allocate statically.
	* grub-core/lib/xzembed/xz_dec_lzma2.c [GRUB_EMBED_DECOMPRESSOR]:
	Allocate statically or use scratch. Don't check CRC32.
	* grub-core/lib/xzembed/xz_dec_stream.c [GRUB_EMBED_DECOMPRESSOR]:
	Allocate statically. Don't check CRC32.
	* include/grub/decompressor.h: New file.
	* include/grub/offsets.h (GRUB_KERNEL_MIPS_YEELOONG_RAW_SIZE):
	Removed.
	(GRUB_KERNEL_MIPS_YEELOONG_UNCOMPRESSED_SIZE): New field.
	(GRUB_KERNEL_MIPS_YEELOONG_TOTAL_MODULE_SIZE): Adjusted.
	(GRUB_KERNEL_MIPS_YEELOONG_PREFIX): Likewise.
	(GRUB_KERNEL_MIPS_YEELOONG_PREFIX_END): Likewise.
	(GRUB_KERNEL_MACHINE_UNCOMPRESSED_SIZE): New define.
	* util/grub-mkimage.c (grub_compression_t): New type.
	(PLATFORM_FLAGS_DECOMPRESSORS): New flag.
	(image_target_desc): New field default_compression.
	(image_targets): Adjust yeeloong targets.
	(compress_kernel_xz) [HAVE_LIBLZMA]: New function.
	(compress_kernel): New parameter comp.
	(generate_image): Likewise. Handle new compression case.
	(options): New option --compression
	(help): Likewise.
	(main): Handle new option.