[clang] [Clang][CodeGen] Fix bad codegen when building Clang with latest MSVC (PR #102681)

[David Chisnall via cfe-commits]

davidchisnall wrote:

The new version is probably slightly more readable than mine, but I don’t really understand how it would affect codegen with UT C. No objections.

https://github.com/llvm/llvm-project/pull/102681