job_event_* functions can all be static, as they are not used
outside job.c.

Same applies for job_txn_add_job().

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20220926093214.506243-4-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>