jmx-dev RFR 8038826: sun/management/jmxremote/startstop/JMXStartStopTest.java fails with "should report port in use"

[Jaroslav Bachorik]

Please, review the following test fix.

Issue : https://bugs.openjdk.java.net/browse/JDK-8038826
Webrev: http://cr.openjdk.java.net/~jbachorik/8038826/webrev.00

The test used to use a final array to pass flags between threads. 
Obviously not a great choice from the point of visibility. Therefore it 
was failing intermittently when it should have passed, according to logs.

The fix is to use an atomic int value to indicate a mode of failure.

Thanks,

-JB-