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

[Mikael Holmén via llvm-commits]

mikaelholmen wrote:

> Sorry for the bother; fixed in [251958f](https://github.com/llvm/llvm-project/commit/251958f3570730f58d1337ac6d00f03ee6a839fe). @OCHyams could you do some post-commit review on that?

Thank you! I've verified that the fix solves the problems we saw.

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