[llvm] [DwarfGenerator] Calculate relative offset according to Dwarf Version (PR #84847)

[James Henderson via llvm-commits]

jh7370 wrote:

Do you have commit access? You can squash and merge this as soon as you're ready, if so. Alternatively, I can do so if you need me to.

https://github.com/llvm/llvm-project/pull/84847