YARN-1775. Enhanced ProcfsBasedProcessTree to optionally add the ability to use smaps for obtaining used memory information. Contributed by Rajesh Balamohan.
svn merge --ignore-ancestry -c 1580087 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.4@1580089 13f79535-47bb-0310-9956-ffa450edef68