Return "[Codegenprepare][X86] Use usub with overflow opt for IV increment"

The patch did not account for one corner case where cmp does not dominate
the loop latch. This patch adds this check, hopefully it's cheap because
the CFG does not change during the transform, so DT queries should be
executed quickly.

If you see compile time slowness from this, please revert.

Differential Revision: https://reviews.llvm.org/D96119