layer.conf: Add in useradd dependencies as ABISAFE dependencies

Currently allarch recipes using useradd rebuild each time MACHINE
changes which is not desireable. Adding the useradd dependencies
to this list ensures they do not change under these circumstances.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steffen Sledz <sledz@dresearch-fe.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
update-rc.d/systemd: Remove OVERRIDES dependency

Taking run-postinsts and building for two machines which have different
OVERRIDES leads to two different sets of stamps for an allarch package.

We don't need to depend on OVERRIDES in these classes, the end resulting
variables are good enough. We can therefore exclude the dependency
and allow a single package to be generated for run-postinsts.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steffen Sledz <sledz@dresearch-fe.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
layer.conf: Mark opkg-utils as ABISAFE for update-alternatives usage

Currently linux-firmware rebuilds for each machine due to its usage of
update-alternatives which in turn means a dependency on opkg-utils.
Marking opkg-utils as ABISAFE is the only option we have right now
to avoid this.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steffen Sledz <sledz@dresearch-fe.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>