osd: rename variables in project_pg_history.
osd: rename variables in project_pg_history.

These are always the current sets; I don't know why they would
ever be called lastup and it confused me when I started looking
at this. Confusion means something needs to change!

Signed-off-by: Greg Farnum <0bcb4295d38ee745130ea5f2bb88ef4eef474e61@dreamhost.com>

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