Fix compile error on Ubuntu.
Fix compile error on Ubuntu.

duke8253/trafficserver,PSUdaemon/trafficserver,vmamidi/trafficserver,pbchou/trafficserver,SolidWallOfCode/trafficserver,SolidWallOfCode/trafficserver,duke8253/trafficserver,dyrock/trafficserver,vmamidi/trafficserver,vmamidi/trafficserver,SolidWallOfCode/trafficserver,persiaAziz/trafficserver,PSUdaemon/trafficserver,persiaAziz/trafficserver,davidbz/trafficserver,dyrock/trafficserver,duke8253/trafficserver,dyrock/trafficserver,duke8253/trafficserver,reveller/trafficserver,pbchou/trafficserver,reveller/trafficserver,persiaAziz/trafficserver,PSUdaemon/trafficserver,PSUdaemon/trafficserver,bryancall/trafficserver,davidbz/trafficserver,bryancall/trafficserver,pbchou/trafficserver,bryancall/trafficserver,pbchou/trafficserver,chitianhao/trafficserver,reveller/trafficserver,pbchou/trafficserver,PSUdaemon/trafficserver,dyrock/trafficserver,davidbz/trafficserver,persiaAziz/trafficserver,chitianhao/trafficserver,chitianhao/trafficserver,persiaAziz/trafficserver,chitianhao/trafficserver,reveller/trafficserver,SolidWallOfCode/trafficserver,dyrock/trafficserver,pbchou/trafficserver,PSUdaemon/trafficserver,bryancall/trafficserver,dyrock/trafficserver,duke8253/trafficserver,reveller/trafficserver,bryancall/trafficserver,PSUdaemon/trafficserver,duke8253/trafficserver,chitianhao/trafficserver,SolidWallOfCode/trafficserver,dyrock/trafficserver,PSUdaemon/trafficserver,chitianhao/trafficserver,vmamidi/trafficserver,davidbz/trafficserver,chitianhao/trafficserver,vmamidi/trafficserver,persiaAziz/trafficserver,SolidWallOfCode/trafficserver,PSUdaemon/trafficserver,davidbz/trafficserver,persiaAziz/trafficserver,persiaAziz/trafficserver,reveller/trafficserver,davidbz/trafficserver,reveller/trafficserver,SolidWallOfCode/trafficserver,reveller/trafficserver,vmamidi/trafficserver,duke8253/trafficserver,reveller/trafficserver,bryancall/trafficserver