Fix for building with icc.
Fix for building with icc.

Summary: Closes https://github.com/facebook/folly/pull/649

Reviewed By: Orvid

Differential Revision: D5535534

Pulled By: yfeldblum

fbshipit-source-id: 641186d6171479755bd9471a484b8b3c2ab62418

facebook/folly,Orvid/folly,rklabs/folly,rklabs/folly,facebook/folly,rklabs/folly,Orvid/folly,Orvid/folly,facebook/folly,facebook/folly,facebook/folly,rklabs/folly,Orvid/folly,Orvid/folly,rklabs/folly