Disallow thread local concepts to allow fibers move between threads @notl

[Sebastiaan Koppe]

On Friday, 14 June 2024 at 17:30:27 UTC, Richard (Rikki) Andrew 
Cattermole wrote:
>
> Destroy!

Instead of introducing 3 new attributes I think its a lot better 
to make TLS @system instead.

TLS should be used sparingly anyway, so making its usage more 
difficult is a lot cheaper than extra attributes than make 
everything else harder.