Remove superfluous variable setting, the script will exit anyway.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@6146 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -931,7 +931,6 @@ if test "$vorbis" = "yes" ; then
     if test "$libogg" = "no"; then
         echo "libogg must be enabled to enable Vorbis."
         fail="yes"
-        vorbis="no"
     fi
 fi