HADOOP-9559. Merging change r1604225 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1604227 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6535. Merge r1604226 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1604228 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5830. Added back the private API HostUtil.getTaskLogUrl(..) for binary compatibility with older clients like Hive 0.13. Contributed by Akira Ajisaka.
svn merge --ignore-ancestry -c 1604230 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1604231 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6557. Merge r1604242 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1604244 13f79535-47bb-0310-9956-ffa450edef68