[clang] clang: Forward exception_model flag for bitcode inputs (PR #146342)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> This broke building C++ modules for mingw targets. Repro:
> 
> `empty.cppm`:
> 
> ```c++
> export module empty;
> ```
> 
>  ```
> $ clang -target x86_64-windows-gnu -x c++-module empty.cppm -c -o empty.cppm.obj -std=gnu++23
> error: invalid value 'seh' in '-exception-model=seh'
> ```

https://github.com/llvm/llvm-project/pull/146643

I for some reason have to repeat the reproducer exactly this way; if I just run cc1 with the same triple and flags it seems to work? 

https://github.com/llvm/llvm-project/pull/146342