RFR: Replace BacktraceBuilder and allocation safepoints in async_get_stack_trace [v2]

[Serguei Spitsyn]

On Wed, 5 May 2021 21:20:31 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Something like this.  I'm still running tests.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Cosmetic cleanups.

Marked as reviewed by sspitsyn (Committer).

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

PR: https://git.openjdk.java.net/loom/pull/40