[llvm] [Symbolizer, DebugInfo] Clean up LLVMSymbolizer API: const string& -> StringRef (PR #104541)

[Fangrui Song via llvm-commits]

https://github.com/MaskRay approved this pull request.

I've tested that this passed check-llvm asan.

https://github.com/llvm/llvm-project/pull/104541