HADOOP-9439.  JniBasedUnixGroupsMapping: fix some crash bugs (Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1496112 13f79535-47bb-0310-9956-ffa450edef68
YARN-736. Add a multi-resource fair sharing metric. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1496153 13f79535-47bb-0310-9956-ffa450edef68