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

[Javier Lopez-Gomez via llvm-commits]

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jalopezg-git wrote:

I don't think we need these changes to `LVRange`, as I have seen no constructor being called w/ a value different from the default (`std::nullopt`).

That would save space, as we don't need the `TombstoneAddress` additional member.  WDYT?

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