LUCENE-5701: Move core closed listeners to AtomicReader.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1597180 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5701: This is a 4.9 change.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1597181 13f79535-47bb-0310-9956-ffa450edef68