[clang] [llvm] [llvm] Fix the MCSubtargetInfo used for module-level assembly. (PR #97685)

[Peter Collingbourne via cfe-commits]

pcc wrote:

I'd be fine with landing this change now, as it makes things less broken than they are now. For module level asm we arguably need a way of attaching target-cpu and target-features to the asm, which is orthogonal to what my change is doing.

https://github.com/llvm/llvm-project/pull/97685