[llvm] [llvm] Set emulated-tls by default for x86_64-windows-gnu target (PR #79542)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo requested changes to this pull request.

Marking as changes requested, to indicate that we don't want to merge this as such quite yet.

https://github.com/llvm/llvm-project/pull/79542