[llvm] [InstCombine] Add test for freeze of GEP with recurrence offset (NFC) (PR #145541)

[David Sherwood via llvm-commits]

david-arm wrote:

@c-rhodes is on holiday for a while, but given this patch is only adding tests I figured it should ok for me to merge on his behalf.

https://github.com/llvm/llvm-project/pull/145541