Fixing a Not_found and evar not found anomaly found in ATBR,
related to setoid_rewrite t where t containts evars, to be added
to the goal evars.


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16573 85f007b7-540e-0410-9357-904b9bb8a0f7