Use attribute-based suppression in free-invoke traits
Use attribute-based suppression in free-invoke traits

Summary: [Folly] Use attribute-based suppression in free-invoke traits v.s. pragma-based suppression for suppressing warnings about unused functions.

Reviewed By: vitaut

Differential Revision: D18112966

fbshipit-source-id: 2519f94d4ff4609c8418d4fd009a24acefe23ab2

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