Use CHECK-DAG in a test so that it isn't sensitive to metadata order.

This was failing on an internal branch where the order was different for
some reason. <rdar://problem/16407581>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@204633 91177308-0d34-0410-b5e6-96231b3b80d8