RFR(S): JDK-8054066 com/sun/jdi/DoubleAgentTest.java fails with timeout

[Dmitry Samersoff]

Please review testfix.

http://cr.openjdk.java.net/~dsamersoff/JDK-8054066/webrev.01/

The test is rewritten to use testlibrary instead of custom code.

-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.