Remove the Kerberos portability header
Remove the Kerberos portability header

Summary: It's no longer needed.

Reviewed By: yfeldblum

Differential Revision: D9847073

fbshipit-source-id: 072f4e5fc207ab199689e42c4f492d4fcb67aa8e

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