[llvm] Support: unlock Windows API support, switch to Windows 10 RS1+ APIs (PR #102240)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> @mstorsjo I'm not sure a fallback is really that simple. This impacts the semantics - the behaviour between the two versions is pretty different.

I'm not quite sure I understand the distinction. If running on an old version, where the newer API is unavailable and we'd fall back on the old one, things would work like they have worked so far, right? And that behaviour has been acceptable in mosts cases, except in some specific corner cases?

https://github.com/llvm/llvm-project/pull/102240