Fix typo in checking hw checksum support
Fix typo in checking hw checksum support

Summary: [Folly] Fix technical typo in checking hw checksum support, but which makes no practical difference.

Differential Revision: D21689112

fbshipit-source-id: 8ad71d20a561f4bbf5c413ce94e7bec227d9d940

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