RFR: 8288752: Split thread implementation files [v2]

[Robbin Ehn]

On Tue, 21 Jun 2022 12:22:46 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This changes splits thread.hpp/cpp into javaThread, and threads files.
>> 
>> I left the commits intact to see better the progression of changes, but most files are include file changes.  The only tricky parts are that some files were included in thread.hpp, like mutexLocker.cpp, which has to be included in the files that need it.
>> 
>> I didn't update the copyrights to save diffs but will before integration.
>> Also I won't integrate until after Dan's JDK 19 changes are merged into JDK 20.
>> 
>> Tested with tier1-4 on Oracle supported platforms and built on other platforms.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix Shenandoah build.

Looks good, thanks.

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Marked as reviewed by rehn (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9218