[clang] [Clang-REPL] Fix crash during `__run_exit_handlers` with dynamic libraries. (PR #117475)

[Yuxuan Chen via cfe-commits]

https://github.com/yuxuanchen1997 commented:

I landed my previous fix but I found that this test to be more problematic than I originally anticipated. I left some comments. I may send more patches to fix it until I am satisfied. 

https://github.com/llvm/llvm-project/pull/117475