[llvm] Windows: use EcoQoS for ThreadPriority::Background (PR #148797)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> i guess we could also just do the declarations ourselves if they aren't defined ... thoughts?

That's also certainly possible (and there is some precedent for it - that we recently removed in 163871c2d269fe0bf34800739245aa55fe851be0), but it ends up kinda ugly (you either still need to detect - guess - whether the real declarations are available or not, or consistently use a different name to avoid conflicts if the real thing is available). It mostly depends on how complex the missing types are I guess.

https://github.com/llvm/llvm-project/pull/148797