Minor bug fix/update to tracediff util.

util/tracediff:
    Fix bug (used += instead of .= for string concatenation in Perl...
    wrong language!).

    Also updated for new config (s/Universe/root/).

--HG--
extra : convert_revision : 0db3f22794037dc51cc29f78a75bd22012a8ecd9

util/tracediff

@@ -1,5 +1,5 @@
 #! /usr/bin/env perl
-# Copyright (c) 2003-2004 The Regents of The University of Michigan
+# Copyright (c) 2003-2005 The Regents of The University of Michigan
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -53,7 +53,7 @@ $simargs = '"' . join('" "', @ARGV) . '"';
 
 # Redirect config output to cout so that gets diffed too (in case
 # that's the source of the problem).
-$simargs += " --Universe:config_output_file=cout";
+$simargs .= " --root:config_output_file=cout";
 
 $cmd1 = "$sim1 $simargs --stats:text_file=tracediff-$$-1.stats 2>&1 |";
 $cmd2 = "$sim2 $simargs --stats:text_file=tracediff-$$-2.stats 2>&1 |";