h2olog: use bool for boolean
h2olog: use bool for boolean

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