[Issue 19933] MSVC: Undefined std{in,out,err} with -betterC

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19933

--- Comment #1 from kinke <kinke at gmx.net> ---
Quoting myself from
https://github.com/ldc-developers/ldc/issues/3640#issuecomment-757464048:

The MSVC runtime doesn't feature these symbols; MS defines them as macros,
whereas druntime defines and sets them at startup for convenience. [And
druntime of course isn't linked with -betterC.]

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