Summary:
I've broken out the FlatIndex / Distances changes from https://github.com/facebookresearch/faiss/issues/2521 into a separate PR to make things a litle easier to review. This does also include a couple other minor changes to the IVF Flat index which I used to make it easier to dispatch to the RAFT version. I can revert that change too if desired.
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/2707
Reviewed By: wickedfoo
Differential Revision: D44758912
Pulled By: algoriddle
fbshipit-source-id: b2544990b4e941a2558f5004bceec4af4fa1ad09