[bugfix] prevent cnt from underflowing when there is nothing to be recycled
[bugfix] prevent cnt from underflowing when there is nothing to be recycled

yannick/h2o,devnexen/h2o,devnexen/h2o,cwyang/h2o,cwyang/h2o,yannick/h2o,devnexen/h2o,devnexen/h2o,yannick/h2o,cwyang/h2o,h2o/h2o,h2o/h2o,devnexen/h2o,yannick/h2o,yannick/h2o,cwyang/h2o,yannick/h2o,h2o/h2o,cwyang/h2o,yannick/h2o,h2o/h2o,devnexen/h2o,h2o/h2o,devnexen/h2o,devnexen/h2o,h2o/h2o,h2o/h2o,yannick/h2o,yannick/h2o,h2o/h2o,cwyang/h2o,cwyang/h2o,devnexen/h2o,cwyang/h2o,h2o/h2o