Fix ControlledRealTimeReopenThread.close() to wake waiters on interrupt

[iprithv]

close() calls join() on the background thread, then bumps searchingGen to Long.MAX_VALUE and notifyAll()s waiters. If join() throws InterruptedException, the rethrow happened before the bump + notify, so threads in waitForGeneration(targetGen, -1) with targetGen > searchingGen hung forever.

so moved the cleanup into a finally block around join().