[flang-commits] [flang] [flang] Change `uniqueCGIdent` separator from `.` to `_` (PR #71338)

[Fabian Mora via flang-commits]

fabianmcg wrote:

> note that I see at least a couple of other cases where dots may be emitted in assembly names.

@jeanPerier  I was planning to split `.` -> `_` changes into multiple patches, should I bundle all mangling changes in this patch?

https://github.com/llvm/llvm-project/pull/71338