[llvm] [ExpandVariadics] Don't lower unmangled C printf on SPIR-V (PR #206998)

[Nick Sarnie via llvm-commits]

https://github.com/sarnex approved this pull request.

yeah the fact we have to do this is gross, the problem is we want `printf` to be treated like a compiler intrinsic but it's just a regular function, this PR extends the hack we already have (that i added), so imo this pr isnt making the bad situation any worse. lgtm

https://github.com/llvm/llvm-project/pull/206998