Stefan reported this problem that in the future we might start to have
more threads operating on the same Monitor object.  This seris try to
add fundamental support for it.

Patch 1 renames the old out_lock to mon_lock, so that it can cover
more things.

Patch 2 uses the mon_lock to protect Monitor object, at least all the
APIs exported in monitor.h

Patch 3 introduces mon_fdsets_lock to protect mon_fdsets global.

Tests: x86 only, make check, raw iotests, windows build.

Please review.  Thanks,

Peter Xu (3):
  monitor: rename out_lock to mon_lock
  monitor: take mon_lock where proper
  monitor: add lock to protect mon_fdsets

 monitor.c | 120 +++++++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 87 insertions(+), 33 deletions(-)

-- 
2.14.3