Fix race condition in thread startup.
Fix race condition in thread startup.

persiaAziz/trafficserver,dyrock/trafficserver,reveller/trafficserver,reveller/trafficserver,persiaAziz/trafficserver,reveller/trafficserver,reveller/trafficserver,bryancall/trafficserver,SolidWallOfCode/trafficserver,vmamidi/trafficserver,bryancall/trafficserver,clearswift/trafficserver,clearswift/trafficserver,davidbz/trafficserver,davidbz/trafficserver,duke8253/trafficserver,taoyunxing/trafficserver,clearswift/trafficserver,persiaAziz/trafficserver,duke8253/trafficserver,dyrock/trafficserver,davidbz/trafficserver,pbchou/trafficserver,reveller/trafficserver,taoyunxing/trafficserver,taoyunxing/trafficserver,vmamidi/trafficserver,rahmalik/trafficserver,clearswift/trafficserver,rpufky/trafficserver,chitianhao/trafficserver,SolidWallOfCode/trafficserver,vmamidi/trafficserver,pbchou/trafficserver,SolidWallOfCode/trafficserver,duke8253/trafficserver,duke8253/trafficserver,vmamidi/trafficserver,SolidWallOfCode/trafficserver,PSUdaemon/trafficserver,chitianhao/trafficserver,clearswift/trafficserver,reveller/trafficserver,chitianhao/trafficserver,reveller/trafficserver,clearswift/trafficserver,dyrock/trafficserver,rpufky/trafficserver,persiaAziz/trafficserver,rpufky/trafficserver,chitianhao/trafficserver,rpufky/trafficserver,rahmalik/trafficserver,rahmalik/trafficserver,reveller/trafficserver,rahmalik/trafficserver,taoyunxing/trafficserver,vmamidi/trafficserver,chitianhao/trafficserver,clearswift/trafficserver,rpufky/trafficserver,bryancall/trafficserver,taoyunxing/trafficserver,taoyunxing/trafficserver,rpufky/trafficserver,davidbz/trafficserver,davidbz/trafficserver,clearswift/trafficserver,taoyunxing/trafficserver,pbchou/trafficserver,vmamidi/trafficserver,dyrock/trafficserver,rpufky/trafficserver,rpufky/trafficserver,PSUdaemon/trafficserver,persiaAziz/trafficserver,pbchou/trafficserver,PSUdaemon/trafficserver,PSUdaemon/trafficserver,SolidWallOfCode/trafficserver,clearswift/trafficserver,persiaAziz/trafficserver,taoyunxing/trafficserver,dyrock/trafficserver,rahmalik/trafficserver,bryancall/trafficserver,rpufky/trafficserver,SolidWallOfCode/trafficserver,chitianhao/trafficserver,PSUdaemon/trafficserver,dyrock/trafficserver,pbchou/trafficserver,PSUdaemon/trafficserver,taoyunxing/trafficserver,pbchou/trafficserver,rahmalik/trafficserver,rahmalik/trafficserver,PSUdaemon/trafficserver,duke8253/trafficserver,davidbz/trafficserver,reveller/trafficserver,bryancall/trafficserver,dyrock/trafficserver,rahmalik/trafficserver,PSUdaemon/trafficserver,SolidWallOfCode/trafficserver,duke8253/trafficserver,bryancall/trafficserver,persiaAziz/trafficserver,duke8253/trafficserver,rahmalik/trafficserver,persiaAziz/trafficserver,chitianhao/trafficserver,PSUdaemon/trafficserver