RFR: 7902982: jcstress: Add samples for some mutex algorithms [v3]

[Michael Mirwaldt]

On Tue, 29 Jun 2021 13:56:50 GMT, Michael Mirwaldt <github.com+6693355+mmirwaldt at openjdk.org> wrote:

>> In my opinion, half of the story here is to teach the readers, so if you write a trivial `synchronized(lock) { ... } `, then it would be way easier to understand what Dekker algorithm really means.
>> 
>> I think adding blocking primitives here is OK.
>
> Ok, I will

I have now added two more samples: one for synchronized and one for ReentrantLock (ReentrantLock  just for completeness)

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PR: https://git.openjdk.java.net/jcstress/pull/85