[llvm] [DWARF] Emit a worst-case prologue_end flag for pathological inputs (PR #107849)

[Jeremy Morse via llvm-commits]

jmorse wrote:

I've managed to replicate it locally now (I must have been doing something wrong before), should be an easy fix once I've pinned it down, hopefully imminently.

https://github.com/llvm/llvm-project/pull/107849