[clang] [clang] Handle consteval constructors with default initialization. (PR #144970)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

I am a little suspicious of this change because right now we are only calling `ActOnCXXExitDeclInitializer` in `~InitializerScopeRAII()` and now it seems like we need to sprinkle it in other places.

https://github.com/llvm/llvm-project/pull/144970