[llvm] [DebugInfo] Use std::map::try_emplace (NFC) (PR #140839)

[David Blaikie via llvm-commits]

https://github.com/dwblaikie approved this pull request.

I don't feel strongly that this is an improvement... but if it's good for you, I don't object either.

https://github.com/llvm/llvm-project/pull/140839