RFR: 8290059: Do not use std::thread in panama tests

[Maurizio Cimadamore]

On Thu, 21 Jul 2022 18:48:14 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

> This patch removes the use of std::thread from the `java.lang.foreign` tests, and switches to the OS specific thread APIs, in order to change things such as the stack size on some platforms where this is required in the future (see the JBS issue).
> 
> This is done by adding a small header-only library that exposes a function to run code in freshly spawned threads (`run_async`).
> 
> Testing: Running the affected tests on platforms that implement the linker.

Looks good!

test/lib/native/testlib_threads.h line 37:

> 35: typedef HANDLE THREAD_ID;
> 36: 
> 37: #else // !_WIN32

the comments in the #else are inconsistent - some use `!_WIN32`, some use `!windows` others use nothing.

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Marked as reviewed by mcimadamore (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9599