[llvm] [LSR] Strip dead code (NFC) (PR #146109)

[Nikita Popov via llvm-commits]

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

LGTM, but please add a PR description. Nested addrec will handled (i.e. rejected) by pushSCEV().

https://github.com/llvm/llvm-project/pull/146109