ReferenceManager.maybeRefreshBlocking() should not be declared throwing InterruptedException

[Vitaly Funstein]

This probably belongs in the JIRA, and is related to
https://issues.apache.org/jira/browse/LUCENE-4025, but
java.util.Lock.lock() doesn't throw anything. I believe the author of the
change originally meant to use lockInterruptibly() inside but forgot to
adjust the method sig after changing it back to lock().