GDBus: make G_DBUS_DEBUG=authentication work again

This was inadvertently removed in this commit

http://git.gnome.org/browse/glib/commit/?id=1d22b64843c83631bcd0e5255930f3a4e990961e

Signed-off-by: David Zeuthen <davidz@redhat.com>

docs/reference/gio/overview.xml

@@ -365,7 +365,7 @@
            </varlistentry>
            <varlistentry>
              <term>authentication</term>
-             <listitem><para>Information about authentication</para></listitem>
+             <listitem><para>Show information about connection authentication</para></listitem>
            </varlistentry>
          </variablelist>
          The special value <literal>all</literal> can be used to turn on

gio/gdbusauth.c

@@ -48,12 +48,9 @@
 #include "glibintl.h"
 #include "gioalias.h"
 
-#define DEBUG_ENABLED 0
-
 static void
 debug_print (const gchar *message, ...)
 {
-#if DEBUG_ENABLED
   if (G_UNLIKELY (_g_dbus_debug_authentication ()))
     {
       gchar *s;
@@ -79,7 +76,6 @@ debug_print (const gchar *message, ...)
       g_string_free (str, TRUE);
       g_free (s);
     }
-#endif
 }
 
 typedef struct