[llvm] [X86][CodeGen] Fix crash when commute operands of Instruction for code size (PR #79245)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

For 18.x are we better off reverting 134fcc62786d31ab73439201dce2d73808d1785a or cherry picking this patch when its completed? For safety I'm currently preferring reversion.

https://github.com/llvm/llvm-project/pull/79245