Fix PR16797 - Support PHINodes with multiple inputs from the same basic block.
Do not generate new vector values for the same entries because we know that the incoming values
from the same block must be identical.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188185 91177308-0d34-0410-b5e6-96231b3b80d8