Merge pull request #13545 from liewegas/wip-18933

osd: constify OpRequest::get_req(); fix a few cases of operator<< vs mutated message races

Reviewed-by: Josh Durgin <jdurgin@redhat.com>

diff --cc src/messages/MOSDOp.h
Simple merge

diff --cc src/osd/OSD.cc
Simple merge

diff --cc src/osd/PG.cc
Simple merge

diff --cc src/osd/PG.h
Simple merge

diff --cc src/osd/ReplicatedBackend.cc
Simple merge

diff --cc src/osd/ReplicatedBackend.h
Simple merge