[clang] [CLANG][DWARF] Do not emit -ggnu-pubnames for split dwarf version 5. (PR #82840)

[David Blaikie via cfe-commits]

dwblaikie wrote:

If you're debugging with lldb you should probably be using -glldb - if you're doing that, certainly gnu-pubnames should not be enabled by default or implicitly by gsplit-dwarf.

I'd say -gsplit-dwarf -glldb probably doesn't need any names/accelerator table by default (any more than the non-split dwarf should default enable names in -glldb - which, maybe it should be, since it is the default on apple platforms, I think?) - split dwarf for gcc needed to (& I think should still be the default, under -ggdb (the default on Linux etc)) enable gnuoubnames by default for correctness (gdb would assume it was present/accurate and fail lookups, rather than falling back to slow performance/exhaustive search)

https://github.com/llvm/llvm-project/pull/82840