[gtk+] wintab: fix skipping of odd-numbered devices

[Ignacio Casal Quinteiro <icq src gnome org>]

commit 6e197afc4498bf788b498d869d478b03cb7f58d9
Author: Andrew Chadwick <a t chadwick gmail com>
Date:   Sat Nov 19 03:26:29 2016 +0000

    wintab: fix skipping of odd-numbered devices
    
    Fix a regression introduced in 4ce6d1060104e7072eec347370999bfd3fe69dc0
    which causes devices with an odd-numbered zero-based index in the list
    to be passed over incorrectly. This might present as yet another "device
    does not send pressure" bug for ~50% of devices out there.
    
    This commit also closes off another potential segfault for wintab_devices
    lists which have an odd length.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=774699

 gdk/win32/gdkdevicemanager-win32.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/gdk/win32/gdkdevicemanager-win32.c b/gdk/win32/gdkdevicemanager-win32.c
index 7c8794f..9f1f391 100644
--- a/gdk/win32/gdkdevicemanager-win32.c
+++ b/gdk/win32/gdkdevicemanager-win32.c
@@ -852,10 +852,9 @@ gdk_device_manager_find_wintab_device (GdkDeviceManagerWin32 *device_manager,
   GdkDeviceWintab *device;
   GList *tmp_list;
 
-  for (tmp_list = device_manager->wintab_devices; tmp_list; tmp_list = tmp_list->next)
+  for (tmp_list = device_manager->wintab_devices; tmp_list != NULL; tmp_list = tmp_list->next)
     {
       device = tmp_list->data;
-      tmp_list = tmp_list->next;
 
       if (device->hctx == hctx &&
           device->cursor == cursor)