Merge 1550570 from trunk to branch-2 for HADOOP-8753. LocalDirAllocator throws ArithmeticException: divide by zero when there is no available space on configured local dir. Contributed by Benoy Antony.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1550571 13f79535-47bb-0310-9956-ffa450edef68