[at-spi2-atk] Fix some warnings

[Mike Gorse <mgorse src gnome org>]

commit c2f52177b77cc70b02c898fb7b5e5908eb891bfb
Author: Mike Gorse <mgorse novell com>
Date:   Thu Jun 16 10:49:04 2011 -0500

    Fix some warnings

 atk-adaptor/adaptors/table-adaptor.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/atk-adaptor/adaptors/table-adaptor.c b/atk-adaptor/adaptors/table-adaptor.c
index f296816..bd35f5f 100644
--- a/atk-adaptor/adaptors/table-adaptor.c
+++ b/atk-adaptor/adaptors/table-adaptor.c
@@ -199,8 +199,8 @@ impl_GetColumnAtIndex (DBusConnection * bus, DBusMessage * message,
   return reply;
 }
 
-static gchar *
-validate_unallocated_string (gchar *str)
+static const gchar *
+validate_unallocated_string (const gchar *str)
 {
   if (!str)
     return "";