shutdown: Add source information to SHUTDOWN and RESET

Time to wire up all the call sites that request a shutdown or
reset to use the enum added in the previous patch.

It would have been less churn to keep the common case with no
arguments as meaning guest-triggered, and only modified the
host-triggered code paths, via a wrapper function, but then we'd
still have to audit that I didn't miss any host-triggered spots;
changing the signature forces us to double-check that I correctly
categorized all callers.

Since command line options can change whether a guest reset request
causes an actual reset vs. a shutdown, it's easy to also add the
information to reset requests.

Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au> [ppc parts]
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> [SPARC part]
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> [s390x parts]
Message-Id: <20170515214114.15442-5-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
