[clang] [C++20] [Modules] Fix the duplicated static initializer problem (PR #114193)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

Given the problem is very serious and the solution is pretty simple, I'd like to backport this to 19.x.

https://github.com/llvm/llvm-project/pull/114193