[llvm] Add option to log debugging to stdout (PR #91533)

[Patrick Quist via llvm-commits]

partouf wrote:

> Perhaps this can be lit-tested? Checking that some debug output goes to stdout instead of stderr when the flag is enabled?

Thanks for the review, i will have to look into how to add a lit test

https://github.com/llvm/llvm-project/pull/91533