[Issue 23756] Add thread local constructor/destructor pragma

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23756

--- Comment #1 from Richard Cattermole <alphaglosined at gmail.com> ---
This is also handled at the object file level apparently.

https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#tls-callback-functions

There is no reason for SimpleDllMain to exist.

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