[mutter] wayland: Shut up a compiler warning

[Florian Müllner <fmuellner src gnome org>]

commit ead09bf6cca2f19d934906a0108037b594be8099
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Jul 22 23:09:45 2016 +0200

    wayland: Shut up a compiler warning
    
    If the compiler cannot figure out that the condition for setting
    the dev variable is the same as the condition for accessing it,
    it will complain about potential uninitialized use.

 src/wayland/meta-wayland-tablet-seat.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/wayland/meta-wayland-tablet-seat.c b/src/wayland/meta-wayland-tablet-seat.c
index d49238c..9cd8faf 100644
--- a/src/wayland/meta-wayland-tablet-seat.c
+++ b/src/wayland/meta-wayland-tablet-seat.c
@@ -485,7 +485,7 @@ lookup_grouped_devices (ClutterInputDevice     *device,
   MetaBackend *backend = meta_get_backend ();
 
 #ifdef HAVE_NATIVE_BACKEND
-  struct libinput_device *dev, *libinput_device;
+  struct libinput_device *dev = NULL, *libinput_device;
 
   if (META_IS_BACKEND_NATIVE (backend))
     dev = clutter_evdev_input_device_get_libinput_device (device);