This is consistent with what we do for GlobalISel. That way, it is easy
to see whether or not FastISel is able to fully select a function.
At some point we may want to switch that to an optimization remark.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294970 91177308-0d34-0410-b5e6-96231b3b80d8