[lld] [ELF] Change .debug_names tombstone value to UINT32_MAX/UINT64_MAX (PR #74686)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Thank you for putting up a PR. Looking at it I am not sure what the fundamental differences are between your patch and mine. It looks like it is somewhat where my patch has started where additional relocation checks remained, and consequently removed per reviewers suggestions. I thought my PR was going in the right direction per your comment [#70701 (review)](https://github.com/llvm/llvm-project/pull/70701#pullrequestreview-1728476884) Can you explain why the direction you chose to go with is better?
> 
> Thanks.

Hi, yes. I started as trying to preserve the `RelExpr` constraint so that if there is a `R_PC` (error), `-z dead-reloc-in-nonalloc=` does not lose the error. I think other than this difference, functionality-wise the two patches are the same.

https://github.com/llvm/llvm-project/pull/74686