Fix build on 32-bit platforms
Fix build on 32-bit platforms

Summary: This fixes a compile error on 32-bit platforms.

Reviewed By: Orvid

Differential Revision: D8147916

fbshipit-source-id: 86b66b684bed5ffb262630a361cf239948b8bb97

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly