This patch adds support for systemd to execute scripts under /etc/rcS.d.
To be compitable, all services translated from /etc/rcS.d/ scripts would
run before services translated from /etc/rcN.d scripts.
[YOCTO #5159]
(From OE-Core rev: 90bb8e8f9bc2454590d230b209fc749ea7270b9e)
Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>