minor optimisation


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@36375 72102866-910b-0410-8b05-ffd578937521
set closed descriptor to -1 before calling superclass 


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@36376 72102866-910b-0410-8b05-ffd578937521