JDK 9 RFR of 8162902: Add some debugging output to test/java/nio/file/WatchService/DeleteInterference

[Brian Burkhalter]

Please review at your convenience.

Issue:	https://bugs.openjdk.java.net/browse/JDK-8162902
Patch:	http://cr.openjdk.java.net/~bpb/8162902/webrev.00/

Add a few printfs to see whether this can help bracket the problem described in the parent task.

Thanks,

Brian