[llvm] [DebugInfo][RemoveDIs] Have LICM insert at iterator positions (PR #73671)

[Jeremy Morse via llvm-commits]

jmorse wrote:

IIRC ilist iterators have a strong and stable (!) lifetime guarantee, they just wrap instruction pointers most of the time, so the instruction would need to be erased for it to be invalidated.

https://github.com/llvm/llvm-project/pull/73671