[llvm] [llvm-debuginfo-analyzer] Fix crash with WebAssembly dead code (PR #141616)

[Carlos Alberto Enciso via llvm-commits]

CarlosAlbertoEnciso wrote:

Uploaded a new patch that addresses @dwblaikie comments:
- Reduce test case.
- Use std::optional instead of the -2 in the set/unset state.

Rebased to latest `main` branch.

https://github.com/llvm/llvm-project/pull/141616