implement H2O_MULTITHREAD_ONCE
implement H2O_MULTITHREAD_ONCE

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