HADOOP-10079. log a warning message if group resolution takes too long (cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1538108 13f79535-47bb-0310-9956-ffa450edef68
Move HDFS-5035 to 2.2.1 in CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1538124 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4312-trunk-gd