Fix reordering of shuffles and binary operations

Do not apply transformation:

    BinOp(shuffle(v1), shuffle(v2)) -> shuffle(BinOp(v1, v2))

if operands v1 and v2 are of different size.
This change fixes PR19717, which was caused by r208488.
    


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208518 91177308-0d34-0410-b5e6-96231b3b80d8