Update IVFBase.cuh (#1625)
Update IVFBase.cuh (#1625)

Summary:
visual Studio compile problem(undefine reference)

Pull Request resolved: https://github.com/facebookresearch/faiss/pull/1625

Reviewed By: beauby

Differential Revision: D25928255

Pulled By: wickedfoo

fbshipit-source-id: c123eb6f263e8748fca6390beac0f7c0f4868163

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