osd/osd_types: pg_interval_t: include up_primary in pg_interval_t

Nothing uses this, but it triggers a new interval, which makes it confusing
when it is not recording in the interval itself.  Let's add it now.

Signed-off-by: Sage Weil <sage@inktank.com>
osd/osd_types: pg_interval_t: include primaries in operator<<

Also make up vs acting explicit.

Signed-off-by: Sage Weil <sage@inktank.com>