[llvm] [DA] add debug log in ExactRDIVtest (PR #189537)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

Can you update the PR description? I think it may be fine to be empty for such a trivial one, rather than stating the same thing as the title.

https://github.com/llvm/llvm-project/pull/189537