Rework busybox build process, remove compressed includes

Like the kernel, use an output folder to generate includes

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>

Change-Id: I988675b071c7a9a959598734fdaff1fdda4e274f
vi: try to fix cursor with utf-8 content

Change-Id: I45f3bcb1820d661d10a08b4a59d667046cda7179