minor: clean up RRScheduler::incTurnCount
minor: clean up RRScheduler::incTurnCount

hemingcui/xtern_with_paxos,columbia/xtern,columbia/xtern,hemingcui/xtern_with_paxos,columbia/xtern,hemingcui/xtern_with_paxos,hemingcui/xtern_with_paxos,columbia/xtern,columbia/xtern,columbia/xtern,hemingcui/xtern_with_paxos