RFR: Fix held_monitor_count calculation

[Hui Shi]

On Tue, 15 Jun 2021 12:53:17 GMT, Hui Shi <hshi at openjdk.org> wrote:

>> Looks good to me, I think Ron wants to have a look as well.
>
> @rickard @pron  Thanks for your review!

> @huishi-hs Thank you for this valuable contribution!
Welcome! 

@pron @AlanBateman @rickard 
Tencent built a Loom API implemenation (sync with loom API at about 202009 subset and use a JKU similar coroutine runtime) on 8 and now updating to latest API (soon in next release).  https://github.com/Tencent/TencentKona-8/tree/KonaFiber.  The basic idea is develper can use loom API now (on 8 and 11) and easily switch to loom when its ready.

Any commens/questsions are welcome.

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PR: https://git.openjdk.java.net/loom/pull/47