This patch introduces a single, simple, infrastructure to build the
Linux kernel. The configuration is limited to :
* Kernel version: a fixed recent stable version, same as kernel
headers version (for internal toolchains only), custom stable
version, or custom tarball URL
* Kernel patch: either a local file, directory or an URL
* Kernel configuration: either the name of a defconfig or the
location of a custom configuration file
* Kernel image: either uImage, bzImage, zImage or vmlinux.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>