[X86] Use carry flag from add for (seteq (add X, -1), -1).

If we just subtracted 1 and are checking if the result is -1. We can use the carry flag from the ADD instead of an explicit CMP. I'm using the same checks for the add users as EmitTest.

Fixes one case from PR44412

Differential Revision: https://reviews.llvm.org/D72019