RFR: 8292591: Experimentally add back barrier-less Java thread transitions [v3]

[Robbin Ehn]

On Thu, 1 Sep 2022 17:49:59 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   PPC64 port courtesy Martin Doerr
>
> Build changes look good.

@erikj79 I had to remove the ac changes, so there is now no builds changes.
We should probably remove you as reviewer, if you don't want to review the rest? :)

-------------

PR: https://git.openjdk.org/jdk/pull/10123