Better compiler hints in EliasFanoCoding
Better compiler hints in EliasFanoCoding

Summary: Without FDO Clang generates very suboptimal code, adding this hints brings it almost to parity with FDO-compiled code.

Reviewed By: philippv, luciang

Differential Revision: D22139847

fbshipit-source-id: 2cdaf383ca1afd21db1b7ad2aafb3d3c7ce335b0

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