export DefaultTag since it is intended for use with RTTI
export DefaultTag since it is intended for use with RTTI

Reviewed By: simpkins

Differential Revision: D32998904

fbshipit-source-id: ae6d2e5cdfb4c8cbf2863e8f1fad2df3eb33568d

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