client: make fragmap updates a little more space efficient.
client: make fragmap updates a little more space efficient.

If the auth is the same as the parent, don't add to the map (and remove if
it's already there). Absence is interpreted the same as a value of -1.

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