HDFS-6421. Fix vecsum.c compile on BSD and some other systems (Mit Desai via Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596325 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6432. Merge r1596334 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596335 13f79535-47bb-0310-9956-ffa450edef68