Extraction AccessOpaque is now activated again by default (#2952)

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16315 85f007b7-540e-0410-9357-904b9bb8a0f7
Fix for bug #3004 (thanks Hugo!)

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16317 85f007b7-540e-0410-9357-904b9bb8a0f7