- Fix caching of local hint database in typeclasses eauto which could
miss some hypotheses.
- Fix automatic solving of obligation in program, which was not trying
to solve obligations that had no undefined dependencies left.


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/branches/v8.4@16394 85f007b7-540e-0410-9357-904b9bb8a0f7