[llvm] [BranchFolding] Kill common hoisted debug instructions (PR #149999)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse approved this pull request.

LGTM, presumably the absence of DBG_PHIs is checked by the absence of anything between CHECK-NEXT directives?

https://github.com/llvm/llvm-project/pull/149999