[clang] [clang] Inline static helper function in `Compilation.cpp` (PR #152875)

[Thibault Monnier via cfe-commits]

Thibault-Monnier wrote:

Hey, this is my first PR on the llvm-project. I hope it respects the llvm contribution guidelines. Feedback is welcome.

https://github.com/llvm/llvm-project/pull/152875