[llvm] [DebugInfo][GVNSink] Merging debug locations of sinked instructions (PR #92859)

[via llvm-commits]

hiraditya wrote:

LGTM, it'll be nice to have two more tests
1. sinking three way (test18 in llvm/test/Transforms/GVNSink/sink-common-code.ll
2. sinking to a newly created post dominator (@test_pr30244 in llvm/test/Transforms/GVNSink/sink-common-code.ll)

https://github.com/llvm/llvm-project/pull/92859