closing the cloned HDFSIndexInput instances

Warning: Lucene never closes cloned IndexInputs, it will only do this on the original one. The original instance must take care that cloned instances throw AlreadyClosedException when the original one is closed. 

http://grepcode.com/file/repo1.maven.org/maven2/org.apache.lucene/lucene-core/4.0.0/org/apache/lucene/store/IndexInput.java#IndexInput.clone%28%29