[clang] Fix crash with modules and constexpr destructor (PR #69076)

[Shafik Yaghmour via cfe-commits]

shafik wrote:

Please make sure you write a more complete description of the problem and why this solves the problem. The description is usually what goes into the git log and that is very useful for quickly understanding commits and tracking down problems. 

I know some folks edit the description on commit but honestly it is very helpful for the reviewers of your PR to have a full description up front.

https://github.com/llvm/llvm-project/pull/69076