Added XZ Compression

XZ Compression has two main advantages:
a) More RAM! (about 1MB more free fram and yes that matters)
b) Less impact in space of /system partition

Default: Around 3 MB Kernel Size
XZ     : Less than 2 MB Kernel Size

Signed-off-by: Blechd0se <alex.christ@hotmail.de>

Conflicts:
	arch/arm/Kconfig
	arch/arm/boot/compressed/Makefile
	arch/arm/boot/compressed/decompress.c
	arch/arm/configs/ext_config/user_bld.config
	arch/arm/configs/mapphone_defconfig
	init/Kconfig
	scripts/Makefile.lib

Change-Id: If36cbd87bb326ef6df20cc5459cdcb83366c3764