[llvm] [MachinePipeliner] Improve loop carried dependence analysis (PR #94185)

[Santanu Das via llvm-commits]

quic-santdas wrote:

hi @ytmukai, you said the changes inhibit some loops to be pipelined? This patch fixes a missing/incorrect dependency, so I was curious why this should impact some earlier loops which were being pipelined?

https://github.com/llvm/llvm-project/pull/94185