Merge PR #23845 into master

Merge PR #23845 into master

* refs/pull/23845/head:
	osd/OSDMap: include age in up and in counts for ceph status
	mon/OSDMonitor: set new_last_{up,in}_change
	osd/OSDMap: store last_up_change and last_in_change
	mgr/MgrMap: include mgr age in map printer
	mon/MgrMap: track active_changed timestamp
	mon: include mon quorum age in status
	include/utime: add utimespan_str helper

Reviewed-by: John Spray <john.spray@redhat.com>