Fix incorrect memory management in Gtk2::Gdk::Display::list_devices

We do not own the returned list.

NEWS

+Overview of changes in Gtk2 <next>
+==================================
+
+* Fix incorrect memory management in Gtk2::Gdk::Display::list_devices
+
 Overview of changes in Gtk2 1.2494
 ==================================
 

t/GdkDisplay.t

 #!/usr/bin/perl -w
 use strict;
 use Gtk2::TestHelper
-  tests => 26,
+  tests => 27,
   at_least_version => [2, 2, 0, "GdkDisplay is new in 2.2"];
 
 # $Id$
@@ -32,6 +32,8 @@ ok(!$display -> pointer_is_grabbed());
 # $display -> beep();
 $display -> sync();
 
+# Do this twice to ensure we did not damage the list.
+isa_ok(($display -> list_devices())[0], "Gtk2::Gdk::Device");
 isa_ok(($display -> list_devices())[0], "Gtk2::Gdk::Device");
 
 $display -> put_event(Gtk2::Gdk::Event -> new("button-press"));

xs/GdkDisplay.xs

@@ -69,8 +69,6 @@ gdk_display_list_devices (display)
 	devices = gdk_display_list_devices (display);
 	for (i = devices ; i != NULL ; i = i->next)
 		XPUSHs (sv_2mortal (newSVGdkDevice (i->data)));
-	g_list_free (devices);
-	
 
 GdkEvent* gdk_display_get_event (GdkDisplay *display)