[mutter] clutter/evdev: Ensure a valid ClutterEventSequence on single-touch devices

[Carlos Garnacho <carlosg src gnome org>]

commit 73464192959a79f0a5d0db38c4c87f63486eb0af
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Jan 16 19:47:55 2018 +0100

    clutter/evdev: Ensure a valid ClutterEventSequence on single-touch devices
    
    Libinput shall report those as having slot=-1, which gets mistakenly
    translated into the special "NULL" ClutterEventSequence. Making those
    events get a non-NULL sequence will make single touch devices work.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792005

 .../clutter/evdev/clutter-device-manager-evdev.c   |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/clutter/clutter/evdev/clutter-device-manager-evdev.c 
b/clutter/clutter/evdev/clutter-device-manager-evdev.c
index d00c771..2fd66b9 100644
--- a/clutter/clutter/evdev/clutter-device-manager-evdev.c
+++ b/clutter/clutter/evdev/clutter-device-manager-evdev.c
@@ -432,7 +432,7 @@ notify_touch_event (ClutterInputDevice *input_device,
                                                     &event->touch.y);
 
   /* "NULL" sequences are special cased in clutter */
-  event->touch.sequence = GINT_TO_POINTER (slot + 1);
+  event->touch.sequence = GINT_TO_POINTER (MAX (1, slot + 1));
   _clutter_xkb_translate_state (event, seat->xkb, seat->button_state);
 
   if (evtype == CLUTTER_TOUCH_BEGIN ||