I was convinced that it's ok to allow a second i8 return value

I was convinced that it's ok to allow a second i8 return value
to be returned in DL. LLVM's multiple-return-value support is
not ABI-conforming; front-ends that wish to have code emitted
that conforms to an ABI are currently expected to make
arrangements for this on their own rather than assuming that
multiple-return-values will automatically do the right thing.
This commit doesn't fundamentally change this situation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67588 91177308-0d34-0410-b5e6-96231b3b80d8