Bugfix: Correct math to ceil power-of-two pdiff targetting
Bugfix: Correct math to ceil power-of-two pdiff targetting

ahmedbodi/SHA-Eloipool-MMCFE-,pointgaming/point-gaming-btc,jameshilliard/4tar-eloipool,uingei/eloi,cinnamoncoin/eloipool-1,thrasher-/eloipool,thrasher-/eloipool,wizkid057/eloipool,imsaguy/eloipool,uingei/eloipool,svasva/eloipool,thrasher-/eloipool