Drop VIGRA tests
Drop VIGRA tests

As we are no longer shipping the VIGRA bindings, there is no need to
have VIGRA C++ tests. So go ahead and drop them.

jakirkham/rank_filter,nanshe-org/rank_filter,DudLab/rank_filter,jakirkham/rank_filter,jakirkham/rank_filter,nanshe-org/rank_filter,DudLab/rank_filter,nanshe-org/rank_filter,DudLab/rank_filter