[gtk+] button: Update to using GdkEvent API

[Carlos Garnacho <carlosg src gnome org>]

commit fac9ba0fff1f62a889d3d232d94fe2c201e401e6
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Aug 25 16:43:09 2017 +0200

    button: Update to using GdkEvent API

 gtk/gtkbutton.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkbutton.c b/gtk/gtkbutton.c
index 592fa10..43a9af7 100644
--- a/gtk/gtkbutton.c
+++ b/gtk/gtkbutton.c
@@ -328,7 +328,7 @@ touch_release_in_button (GtkButton *button)
   if (!event)
     return FALSE;
 
-  if (event->type != GDK_TOUCH_END)
+  if (gdk_event_get_event_type (event) != GDK_TOUCH_END)
     {
       gdk_event_free (event);
       return FALSE;