[C++ Patch] Avoid uninitialized warning in pt.c

[Paolo Carlini]

Hi,

I think we have to do this, the warning I'm seeing doesn't seem bogus: 
in principle comp_template_args_with_info may leave bad_old_arg and 
bad_new_arg uninitialized.

Ok?

Thanks,
Paolo.

////////////////
2011-10-28  Paolo Carlini  <paolo.carl...@oracle.com>

        * pt.c (unify_pack_expansion): Initialize bad_old_arg and bad_new_arg.
Index: pt.c
===================================================================
--- pt.c        (revision 180623)
+++ pt.c        (working copy)
@@ -15715,7 +15715,7 @@ unify_pack_expansion (tree tparms, tree targs, tre
         }
       else
        {
-         tree bad_old_arg, bad_new_arg;
+         tree bad_old_arg = NULL_TREE, bad_new_arg = NULL_TREE;
          tree old_args = ARGUMENT_PACK_ARGS (old_pack);
 
          if (!comp_template_args_with_info (old_args, new_args,