RFR 8022221: Intermittent test failures in sun/management/jmxremote/startstop/JMXStartStopTest.sh

[Jaroslav Bachorik]

Please, review this test fix.

Issue : https://bugs.openjdk.java.net/browse/JDK-8022221
Webrev: http://cr.openjdk.java.net/~jbachorik/8022221/webrev.00

The test was facing intermittent failures due to not 100% failproof 
interprocess synchronization using lock files. The solution is rewriting 
the shell test to pure Java and use stdout/stderr processing for the 
application started by the test to assess its status.

A part of the change is also few improvements to the 
jdk.testlibrary.ProcessTools.

Thanks,

-JB-