[llvm] [ScalarEvolution] Handle addrec incoming value in isImpliedViaMerge() (PR #126236)

[via llvm-commits]

llvmbot wrote:

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Failed to cherry-pick: 7aed53eb1982113e825534f0f66d0a0e46e7a5ed

https://github.com/llvm/llvm-project/actions/runs/13237235524

Please manually backport the fix and push it to your github fork.  Once this is done, please create a [pull request](https://github.com/llvm/llvm-project/compare)

https://github.com/llvm/llvm-project/pull/126236