Merge pull request #6312 from liewegas/wip-kv

kv: optimize and clean up internal key/value interface

Reviewed-by: Piotr Dałek <piotr.dalek@ts.fujitsu.com>

diff --cc src/Makefile.am
Simple merge

diff --cc src/os/FileStore.cc
Simple merge

diff --cc src/os/KeyValueStore.cc
Simple merge

diff --cc src/os/ObjectStore.h
Simple merge

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

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

diff --cc src/tracing/librados.tp
Simple merge

diff --cc src/tracing/osd.tp
Simple merge