[lld] [lld][ELF] Implement merged .debug_names section. (PR #86508)

[Fangrui Song via llvm-commits]

MaskRay wrote:

I just realized that we did not sort entries by `hash%bucket_count`. This would render the hash lookup table not meaningful.

I have updated https://github.com/MaskRay/llvm-project/tree/lld-debug-names to remove `this->nameEntries`, add `this->nameVec` (previously a local variable), and add sorting.

I just took a quick glance at `bolt/lib/Core/DebugNames.cpp:writeEntries`, which does something similar.

https://github.com/llvm/llvm-project/pull/86508