RFR [6853696] (ref) ReferenceQueue.remove(timeout) may return null even if timeout has not expired

[Ivan Gerasimov]

Hello!

ReferenceQueue.remove(timeout) may return too early, i.e. before the 
specified timeout has elapsed.

Would you please review the fix?
The change also includes a regression test, which can be used to 
demonstrate the issue.

BUGURL: https://bugs.openjdk.java.net/browse/JDK-6853696
WEBREV: http://cr.openjdk.java.net/~igerasim/6853696/0/webrev/

Sincerely yours,
Ivan