added xz support

Conflicts:
	arch/arm/configs/blade_defconfig

	modified:   arch/arm/Kconfig
	modified:   arch/arm/boot/compressed/Makefile
	modified:   arch/arm/boot/compressed/decompress.c
	modified:   arch/arm/boot/compressed/misc.c
	new file:   arch/arm/boot/compressed/piggy.xzkern.S
	new file:   arch/arm/boot/compressed/string.c
	new file:   arch/arm/configs/blade_defconfig
	modified:   arch/arm/configs/cyanogenmod_enrc2b_defconfig