[clang] [CIR] Add BinOpOverflowOp and basic pointer arithmetic support (PR #133118)

[Andy Kaylor via cfe-commits]

https://github.com/andykaylor commented:

I don't see the value of this PR right now. The pointer arithmetic isn't performing the correct arithmetic, and nothing generates the binop.overflow op. It would be more useful to remove the binop.overflow part and add PtrDiffOp.

https://github.com/llvm/llvm-project/pull/133118