[client] wayland: make input handlers aware of multiple surfaces

This prevents input handlers from breaking in presence of subsurfaces,
which are used by libdecor for client-side decorations.

client/displayservers/Wayland/wayland.h

@@ -70,6 +70,8 @@ struct WaylandDSState
 {
   bool pointerGrabbed;
   bool keyboardGrabbed;
+  bool pointerInSurface;
+  bool focusedOnSurface;
 
   struct wl_display * display;
   struct wl_surface * surface;