[lldb] [llvm] [NFC][DebugInfo] Make some block-start-position methods return iterators (PR #124287)

[Harald van Dijk via llvm-commits]

hvdijk wrote:

Yes, thank you, something like that looks great! I should be able to do some testing with that tomorrow to check to make sure I am not missing anything.

https://github.com/llvm/llvm-project/pull/124287