Merge pull request #9187 from liewegas/wip-cppool

rados: refuse to cppool if there are snaps; warn about user_version

Reviewed-by: Sage Weil <sage@redhat.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>
Reviewed-by: Samuel Just <sjust@redhat.com>
Reviewed-by: Yehuda Sadeh <yehuda@redhat.com>

diff --cc src/include/rados/librados.hpp
Simple merge

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

diff --cc src/tools/rados/rados.cc
Simple merge