PG: mark scrubmap entry as not absent when we see an update
PG: mark scrubmap entry as not absent when we see an update

Previously, there would be an assert failure in _scan_list if we see an
object deleted and then recreated.

Signed-off-by: Samuel Just <4c46b94684b338bae1ed5e7e1321718dd75401cc@dreamhost.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph