[llvm] [DWARF] Disable generation of cross-CU references for DWARF V2 (PR #192516)

[via llvm-commits]

Nadharm wrote:

@ayermolo @echristo @enferex @dwblaikie ping for review please.

Is there some agreement among DWARF producers/consumers for whether the DWARF FAQ's (https://dwarfstd.org/faq.html) suggestion to generate the V3 format should be respected or ignored?

https://github.com/llvm/llvm-project/pull/192516