[clang] [llvm] [IR] Don't use TrackingMDNodeRef for DebugLoc (PR #200649)

[Alexis Engelke via cfe-commits]

aengelke wrote:

Can you provide more details: Is this upstream or downstream? If upstream, where is this tested? If downstream, can you temporarily revert downstream? Given the huge performance improvements, I'd rather not revert unless this breaks something in-tree right now. Also note that larger changes to the DebugLoc representation are coming up (see Discourse), so you'd need to eventually migrate away from depending on TrackingMDNodeRef anyway.

https://github.com/llvm/llvm-project/pull/200649