SLPVectorizer: Don't vectorize phi nodes that use invoke values

We can't insert an insertelement after an invoke. We would have to split a
critical edge. So when we see a phi node that uses an invoke we just give up.

radar://14990770

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190871 91177308-0d34-0410-b5e6-96231b3b80d8