[clang] [C++20][Modules] Restore inliness of constexpr/consteval functions defined in-class (PR #109470)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

The link you gave for the regression is not a llvm commit, is that the correct commit you meant to point to?

https://github.com/llvm/llvm-project/pull/109470