Use new CHECK-DAG support to stabilize CodeGen/PowerPC/recipest.ll

While testing some experimental code to add vector-scalar registers to
PowerPC, I noticed that a couple of independent instructions were
flipped by the scheduler.  The new CHECK-DAG support is perfect for
avoiding this problem.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182020 91177308-0d34-0410-b5e6-96231b3b80d8