Merge pull request #8789 from vuhuong/wip-msgr-flex-prop-list

msgr,xio: flexible Messenger::create options

Reviewed-by: Sage Weil <sage@redhat.com>
Reviewed-by: Gregory Farnum <gfarnum@redhat.com>
Reviewed-by: Haomai Wang <haomai@xsky.com>
Reviewed-by: Casey Bodley <cbodley@redhat.com>

diff --cc src/ceph_mds.cc
Simple merge

diff --cc src/msg/xio/XioMessenger.cc
Simple merge