HADOOP-8075. Lower native-hadoop library log from info to debug. (Hızır Sefa İrken via eli)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1444853 13f79535-47bb-0310-9956-ffa450edef68
Updating release date for 0.23.6

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1444854 13f79535-47bb-0310-9956-ffa450edef68