RFR (XS): 8023138: TEST_BUG java/lang/instrument/PremainClass/NoPremainAgent.sh fails intermittently

[Mattias Tobiasson]

Hi,
Could you please review this fix.
The tests for java/lang/instrument/PremainClass/PremainAgent has been ported from script to java.
The purpose is to make the tests more stable and easier to maintain. 

Thanks,
Mattias

Webrev:
http://cr.openjdk.java.net/~ykantser/8023138/webrev.00/

Bug:
https://bugs.openjdk.java.net/browse/JDK-8023138