[at-spi2-atk] Fix a warning caused by a missing const

[Mike Gorse <mgorse src gnome org>]

commit 7787ad5cbdf4b1f130008a2506463b6d824db8df
Author: Mike Gorse <mgorse novell com>
Date:   Mon Jan 2 20:17:18 2012 -0600

    Fix a warning caused by a missing const

 atk-adaptor/event.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/atk-adaptor/event.c b/atk-adaptor/event.c
index ef6b964..6cf19fa 100644
--- a/atk-adaptor/event.c
+++ b/atk-adaptor/event.c
@@ -424,7 +424,7 @@ signal_is_needed (const gchar *klass, const gchar *major, const gchar *minor)
 /* Convert a : to a / so that listeners can use arg0path to match only
  *  * the prefix */
 static char *
-adapt_minor_for_dbus (char *source)
+adapt_minor_for_dbus (const char *source)
 {
   gchar *ret = g_strdup (source);
   int i = strcspn (ret, ":");