[llvm] [CMake] Options to control generation of reproducers (PR #143037)

[Jon Roelofs via llvm-commits]

jroelofs wrote:

> we don't provide any control over the reproducers (whether to generate them only for compiler crashes or linker crashes as well) or their location

Not to dissuade you from this patch (which I think is great!), but FWIW, you can set the `CLANG_CRASH_DIAGNOSTICS_DIR` environment variable, and clang will dump crash reproducers in that path. This is great for CI, especially in non-llvm projects.

https://github.com/llvm/llvm-project/pull/143037