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

[Fabian Mora via flang-commits]

fabianmcg wrote:

> Regarding '$', are we sure that all assembly languages are OK with it?

@jeanPerier that's a good point we'd end up circling back if we encounter  `$` is not valid in a given target. What about an upper case separator, or a series of upper case chars?

1. `.` -> `X` ?
2. `.` -> `X_X` ?

I'm suggesting `X` because I think it's not in use.

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