[llvm] [Coro] Amortize debug info processing cost in CoroSplit (PR #109032)

[Artem Pianykh via llvm-commits]

artempyanykh wrote:

Thanks @felipepiovezan! There's some commentary around the commits in [this discourse topic](https://discourse.llvm.org/t/rfc-amortizing-debug-info-processing-cost-in-corosplit/81275), in case it's useful.

https://github.com/llvm/llvm-project/pull/109032