Fix for Issue #86 (https://github.com/NVlabs/cub/issues/86, Incorrect results with ReduceByKey).  The issue was that the final value only incorporated addends from the last block in the event that the number of items is a whole multiple of block size.  
Fix for Issue #86 (https://github.com/NVlabs/cub/issues/86, Incorrect
results with ReduceByKey).  The issue was that the final value only
incorporated addends from the last block in the event that the number of
items is a whole multiple of block size.  

Former-commit-id: 2d22afa36d3854b9b3b25c2aba1c806634054f7f
NVIDIA/cub,NVlabs/cub,NVlabs/CUB