[mutter] Fix string format build error

[Olav Vitters <ovitters src gnome org>]

commit 028157081c0428bac1269078dd7f3360e3810824
Author: Olav Vitters <olav vitters nl>
Date:   Thu Sep 22 21:00:29 2016 +0200

    Fix string format build error
    
    backends/meta-input-settings.c:1245:27: error: format '%lx' expects
    argument of type 'long unsigned int', but argument 3 has type 'guint64
    {aka long long unsigned int}' [-Werror=format=]

 src/backends/meta-input-settings.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/backends/meta-input-settings.c b/src/backends/meta-input-settings.c
index ae17f7b..74cf30a 100644
--- a/src/backends/meta-input-settings.c
+++ b/src/backends/meta-input-settings.c
@@ -1242,7 +1242,7 @@ lookup_tool_settings (ClutterInputDeviceTool *tool,
 
   tool_id = clutter_input_device_tool_get_id (tool);
   device_id = get_tablet_settings_id (device, lookup_mapping_info (device));
-  path = g_strdup_printf ("/org/gnome/settings-daemon/peripherals/wacom/%s/%lx/",
+  path = g_strdup_printf ("/org/gnome/settings-daemon/peripherals/wacom/%s/%" G_GUINT64_FORMAT "/",
                           device_id, tool_id);
   tool_settings = tool_settings_new (tool, path);
   g_object_set_qdata_full (G_OBJECT (tool), quark_tool_settings, tool_settings,