Merge pull request #5524 from tchaikov/wip-monstore-cache

mon: add a cache layer over MonitorDBStore

Reviewed-by: Joao Eduardo Luis <joao@suse.de>
Reviewed-by: Sage Weil <sage@redhat.com>

diff --cc src/common/config_opts.h
Simple merge

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