[compiler-rt] [compiler-rt] Add MinGW GCC support for Windows sanitizer runtimes (PR #209902)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> It would be nice to extract isolated patches into separate descriptions why each of them is needed. Some could be trivial.
> 
> It could be easier to iterated by stamping obvious changes, and never see them again, than getting back to them on each review iteration.

+1, it would be a much lower threshold for approving things if it is split up into smaller piecemeal changes, i.e. separate PRs, that each of them only do one kind of change.

https://github.com/llvm/llvm-project/pull/209902