Merge PR #27146 into master

* refs/pull/27146/head:
	mon/MonMap: add min_quorum_size() helper
	mon/MDSMonitor: add 'mds ok-to-stop' command
	mon: add 'mon ok-to-{stop,add-offline,rm}' commands

Reviewed-by: Kefu Chai <kchai@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>

diff --cc src/mon/MonCommands.h
Simple merge

diff --cc src/mon/MonMap.h
Simple merge

diff --cc src/mon/Monitor.cc
Simple merge