Backport r16394 from 8.4:
- 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.

Fix a warning in fourierR.ml.


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16395 85f007b7-540e-0410-9357-904b9bb8a0f7