[9] RFR: 8164592: java/net/MulticastSocket/NoLoopbackPackets.java tests may leave a daemon thread

[Artem Smotrakov]

Hello,

Please review the following patch for NoLoopbackPackets.java test.

The test starts a daemon thread which has an infinite loop. If jtreg 
uses the same JVM to run multiple tests (agent VM), then this thread 
will be keep running until the agent VM stops. This is not good, it 
would be better to stop the thread when the test is done.

Webrev: http://cr.openjdk.java.net/~asmotrak/8164592/webrev.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-8164592

Artem