Added explicit pub to several conditions.  Enables completion of #6009.
Make non-pub condition! expand to non-pub mod.  Fix #6009.
auto merge of #8977 : pnkfelix/rust/fsk-followup-on-6009-rebased, r=alexcrichton

Fix #6009.  Rebased version of #8970.  Inherits review from alexcrichton.