Some help with core/thread refactoring

[Stefanos Baziotis]

On Saturday, 10 August 2019 at 14:56:45 UTC, Seb wrote:
> Druntime hasn't switched from AppVeyor to Azure.

Ah ok. Is the auto-tester working?
I get failure in all platforms for what seem completely unrelated 
reasons with the PR. i.e. DMD failed tests.

https://auto-tester.puremagic.com/pull-history.ghtml?projectid=1&repoid=2&pullid=2689