Merge pull request #14866 from chardan/jfw-wip-halflife_atomic_t-varan

common,test: migrate atomic_t to std::atomic

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

diff --cc src/common/buffer.cc
Simple merge

diff --cc src/common/perf_counters.cc
Simple merge

diff --cc src/mgr/ClusterState.cc
Simple merge

diff --cc src/mgr/DaemonServer.cc
Simple merge

diff --cc src/mgr/Mgr.cc
Simple merge

diff --cc src/mgr/MgrClient.cc
Simple merge

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

diff --cc src/msg/Message.cc
Simple merge

diff --cc src/msg/async/rdma/RDMAConnectedSocketImpl.cc
Simple merge