fate: delete output files from successful tests

Originally committed as revision 24150 to svn://svn.ffmpeg.org/ffmpeg/trunk

tests/fate-run.sh

@@ -32,3 +32,5 @@ case $cmp in
     diff)   diff -u -w "$ref" "$outfile"            ;;
     oneoff) oneoff     "$ref" "$outfile" "$fuzz"    ;;
 esac
+
+test $? = 0 && rm $outfile