Merge pull request #7843 from branch-predictor/bp-smart-async-wp

msg/async: Implement smarter worker thread selection

Reviewed-by: Haomai Wang <haomai@xsky.com>

diff --cc src/common/config_opts.h
Simple merge

diff --cc src/msg/async/AsyncConnection.cc
Simple merge

diff --cc src/msg/async/AsyncMessenger.cc
Simple merge