Separating whitebox-api from jcstress-core - issues with 3rd-party libraries

[Jerzy Krolak]

Hello,

I've tried to run a jcstress suite with a 3rd-party library in it and faced
a problem - the lib could not be used within the boot classpath.

At the moment, the whole jcstress-core and my libraries need to go into
bootclasspath, and I think that the only reason is the WhiteBox class in
the jar.

I've separated these on my PC and could successfully load a simple
Spring-based application.
A jar with a single WhiteBox went to the bootclasspath, and jcstress-core
stayed in the cp.

There are two potential issues with my patch:
- a forked run loads the whitebox jar twice (one in boot cp and the other
in regular one) - can it cause side effects?
- an unforked run won't load whitebox into bootcp at all (but I think it's
the same behaviour as before) - same question here.

The above issues can be fixed easily, but I wanted to keep the patch file
small for now.

I've tested the patch with jcstress suite and a recent jdk-9 (build 157).

Thanks,
Jerzy