[llvm] [Instcombine] Fix crash in foldMinimumMaximumSharedOp. (PR #173705)

[Justin Lebar via llvm-commits]

jlebar wrote:

> Do you need someone to merge the change for you?

I just requested to get my commit access restored.  Why don't we race that against getting reviews for the 4 PRs I sent; if I don't have commit access once all four of those are ready, then I'd appreciate help merging!

https://github.com/llvm/llvm-project/pull/173705