cronie: Convert crontab to a system user

crontab is meant to be a system user, not a normal user of the system
so lets pass the correct parameters to the system. If we don't do this
it interferes with the setup of normal users, particularly if some
preset list of users is desired.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
archive-*-source.bbclass: handle dependency in anonymous function

Using "before do_rootfs" would have this task added to do_rootfs
dependencies regardless of the filtering options. Instead, add this
dependency in the anonymous python function.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>