use avx blend for cardinality 4 shuffles with pattern (0 or 4,1 or 5,2 or 6,3 or 7)
fix bug that prevented unit test compilation.

shuffle tests pass now.
unit tests for avx blend shuffle
Merge pull request #772 from khegeman/avx_shuffle_blend

Use avx blend for cardinality 4 shuffles with pattern (0 or 4, 1 or 5, 2 or 6,3 or 7)