[glibmm] Glib::DateTime: Fix compare() and equal().

[Kjell Ahlstedt <kjellahl src gnome org>]

commit ef44e0800c8a7601cc7a76af8c362407aa79b5f2
Author: Kjell Ahlstedt <kjell ahlstedt bredband net>
Date:   Tue Jul 23 16:02:32 2013 +0200

    Glib::DateTime: Fix compare() and equal().
    
    * glib/src/datetime.hg: Fix the conversion from const DateTime& to
    gconstpointer. Bug #704639.

 glib/src/datetime.hg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/glib/src/datetime.hg b/glib/src/datetime.hg
index 167a412..601d977 100644
--- a/glib/src/datetime.hg
+++ b/glib/src/datetime.hg
@@ -101,7 +101,7 @@ public:
    */
   _WRAP_METHOD(TimeSpan difference(const DateTime& other) const, g_date_time_difference)
 
-#m4 _CONVERSION(`const DateTime&',`gconstpointer',`static_cast<gconstpointer>(&($3))')
+#m4 _CONVERSION(`const DateTime&',`gconstpointer',`static_cast<gconstpointer>($3.gobj())')
   /** A comparison function for DateTimes that is suitable
    * as a CompareFunc.
    *