Fix creating illegal setcc cond codes.

If GT/UGT or LT/ULT were set to expand, a comparison
with a constant would replace it with the illegal
cond code.

There are several more places later in this function that
will have the same basic problem.

Theoretically R600 should hit this problem for a test,
but for some reason it doesn't.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204727 91177308-0d34-0410-b5e6-96231b3b80d8