RFR: 8295278: Add parallel class loading tests [v3]

[Coleen Phillimore]

On Sat, 15 Oct 2022 01:33:37 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.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update test/hotspot/jtreg/runtime/ParallelLoad/SuperWait/test-classes/A.java
>   
>   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>

Thank you Vladimir and Calvin for the reviews, and @turbanoff for the suggestion to remove the unneeded space.

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