HADOOP-8569. CMakeLists.txt: define _GNU_SOURCE and _LARGEFILE_SOURCE. Contributed by Colin Patrick McCabe.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1449923 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-HADOOP-7435-TEST-branch-2-gd