Merge PR #42014 into master

* refs/pull/42014/head:
	mon/LogMonitor: make 'ceph log last' work with new storage
	mon/LogMonitor: transition log entries on upgrade to quincy
	mon/LogMonitor: store logentries in separate keys
	mon/LogMonitor: replace semi-broken pending_summary with pending_keys
	mon/LogMonitor: externally log events from when we were out of quorum
	mon/LogMonitor: factor logging to file out of update_from_paxos
	mon: funnel SIGHUP handler through handle_mon_signal
	common/LogEntry: add some constness
	mon/LogMonitor: log mkfs in cluster channel
	common/LRUSet: combine lru and hash-based lookup
	mon/LogMonitor: remove stray derr

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

diff --cc src/common/options/mon.yaml.in
Simple merge

diff --cc src/test/common/CMakeLists.txt
Simple merge