TS-3845 Set _current_size to 0 when clearing H2 headers
TS-3845 Set _current_size to 0 when clearing H2 headers

This fixes the issue where HPACK error when trying to delete entries from an
empty table.

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