[clang] [llvm] Reapply "[llvm][IR] Extend BranchWeightMetadata to track provenance of weights" (PR #95136)

[Paul Kirth via cfe-commits]

ilovepi wrote:

So, I think I made a mistake when I started the revert w/ the `revert` button. That created a very long branch name, and I'm a bit concerned I can't update it easily.

I'm about 80% sure `git push git at github.com:llvm/llvm-project.git HEAD:revert-95060-revert-86609-users/ilovepi/spr/llvmir-extend-branchweightmetadata-to-track-provenance-of-weights` will work, but I'm hesitant to push things to the main repo that aren't automated w/ tooling. 

I'm much more confident in my ability to update using a PR started from my fork, so I'm closing in favor of https://github.com/llvm/llvm-project/pull/95281

https://github.com/llvm/llvm-project/pull/95136