[llvm] [llvm-dwp] turn duplicate dwo id into warning, continue to gen dwp (PR #121193)

[Alexander Yermolovich via llvm-commits]

ayermolo wrote:

@clayborg Any thoughts on this?

Maybe leave default an error, with an option to turn it into a warning and skipping?
I don't see the benefit of having two dwo IDS in the cu-index. Also I don't think cu-index algorithm it self allows for duplicates: https://gcc.gnu.org/wiki/DebugFissionDWP

https://github.com/llvm/llvm-project/pull/121193