RFR: 8295278: Add parallel class loading tests

[Vladimir Ivanov]

On Wed, 5 Oct 2022 22:53:48 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> I moved the ParallelLoad test to a subdirectory, and created a new one called CallLoadClass that calls loadClass directly and then waits on the ClassLoader object, while another thread calls forName() to go through the SystemDictionary resolution.
> 
> I also made dedicated tests out of the bugs reported in
> [JDK-4699981](https://bugs.openjdk.org/browse/JDK-4699981) ClassCircularityError thrown without reason during class loading and
> [JDK-4670071](https://bugs.openjdk.org/browse/JDK-4670071) java.lang.ClassLoader.loadClassInternal(String) is too restrictive
> 
> Tested with tier1 on Oracle platforms. These tests are run in tier1.

Looks good.

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Marked as reviewed by vlivanov (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10587