RFR: 8292679: Simplify thread creation in gtest and port 2 tests to new way [v4]

[Thomas Stuefe]

On Wed, 24 Aug 2022 11:25:02 GMT, Johan Sjölén <duke at openjdk.org> wrote:

>> This PR removes a lot of boilerplate that was required when creating multi-threaded tests and ports 2 tests to show that the number of lines of code is significantly reduced and that porting is fairly trivial. The ported tests also serve as an introduction to others who're looking into writing their own multi-threaded tests.
>> 
>> Testing: Ran the ported tests on my machine, also running the tests on x64 {Windows, Linux, Mac OS X],  aarch64 { Linux, Mac OS X} and tier1 for "completeness".
>
> Johan Sjölén has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use symbol_name_length as char array size

LGTM. Thanks for making N a runtime parameter.

..Thomas

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Marked as reviewed by stuefe (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9962