The Ubuntu mainline PPA has kernel.org based kernels for many
kernel releaseis. This commit adds suport for downloading and
converting the 3.16.x long long term support kernel as well
as the current 4.x series. The "mainline.sh" script only
downloads/processes kernels which have not yet been put on
Hub.
The kernels are stored under "linuxkit/kernel-mainline" and are
tagged with the kernel version.
Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
