input: Pass the appropriate pointer type to bindings instead of a seat

Normally we need to check if a seat's [device_type]_count is > 0 before
we can use the associated pointer.  However, in a binding you're
guaranteed that the seat has a device of that type.  If we pass in
that type instead of the seat, it's obvious we don't have to test it.

The bindings can still get the seat pointer via whatever->seat if they
need it.

This is preparation for a follow up patch that prevents direct access
to seat->device_type pointers, and this will save us a few tests at
that point.

Reviewed-by: Jonas Ã…dahl <jadahl@gmail.com>
Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
diff --git a/src/compositor.h b/src/compositor.h
index faaacc2..ee40ecc 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -1149,7 +1149,7 @@
 
 
 struct weston_binding;
-typedef void (*weston_key_binding_handler_t)(struct weston_seat *seat,
+typedef void (*weston_key_binding_handler_t)(struct weston_keyboard *keyboard,
 					     uint32_t time, uint32_t key,
 					     void *data);
 struct weston_binding *
@@ -1159,7 +1159,7 @@
 				  weston_key_binding_handler_t binding,
 				  void *data);
 
-typedef void (*weston_modifier_binding_handler_t)(struct weston_seat *seat,
+typedef void (*weston_modifier_binding_handler_t)(struct weston_keyboard *keyboard,
 					          enum weston_keyboard_modifier modifier,
 					          void *data);
 struct weston_binding *
@@ -1168,7 +1168,7 @@
 				       weston_modifier_binding_handler_t binding,
 				       void *data);
 
-typedef void (*weston_button_binding_handler_t)(struct weston_seat *seat,
+typedef void (*weston_button_binding_handler_t)(struct weston_pointer *pointer,
 						uint32_t time, uint32_t button,
 						void *data);
 struct weston_binding *
@@ -1178,7 +1178,7 @@
 				     weston_button_binding_handler_t binding,
 				     void *data);
 
-typedef void (*weston_touch_binding_handler_t)(struct weston_seat *seat,
+typedef void (*weston_touch_binding_handler_t)(struct weston_touch *touch,
 					       uint32_t time,
 					       void *data);
 struct weston_binding *
@@ -1187,7 +1187,7 @@
 				    weston_touch_binding_handler_t binding,
 				    void *data);
 
-typedef void (*weston_axis_binding_handler_t)(struct weston_seat *seat,
+typedef void (*weston_axis_binding_handler_t)(struct weston_pointer *pointer,
 					      uint32_t time, uint32_t axis,
 					      wl_fixed_t value, void *data);
 struct weston_binding *