[llvm] [llvm] Don't flush llvm::raw_string_ostream (NFC) (PR #110754)

[Nikita Popov via llvm-commits]

nikic wrote:

IIRC there was some disagreement on whether we should be doing this or not, but I don't have the references handy. I think @MaskRay and @aengelke were involved.

https://github.com/llvm/llvm-project/pull/110754