[llvm] [llvm-debuginfo-analyzer] Fix a couple of unhandled DWARF situations leading to a crash (PR #137221)

[Javier Lopez-Gomez via llvm-commits]

jalopezg-git wrote:

@jmorse, @SLTozer, @OCHyams, I think this is ready to merge.  Do you have any additional comments that you would like to see applied?

For the moment, I do not have write access to the repository, so someone would have to do the merge for me :slightly_smiling_face:.

https://github.com/llvm/llvm-project/pull/137221