buildroot

s6-linux-init: new package

This new package provides s6-linux-init, a set of minimalistic tools to
create a s6-based init system, including a /sbin/init program, on a
machine running a Linux kernel.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>