compositor: Change notify_* function to take a weston_seat

Fewer indirections and derefs, and it's also more appropriate for a
backend calling into weston core to pass a weston_seat.
diff --git a/src/compositor-x11.c b/src/compositor-x11.c
index c38d7dc..c02911d 100644
--- a/src/compositor-x11.c
+++ b/src/compositor-x11.c
@@ -641,8 +641,6 @@
 static void
 update_xkb_state(struct x11_compositor *c, xcb_xkb_state_notify_event_t *state)
 {
-	struct wl_seat *seat = &c->core_seat.seat;
-
 	xkb_state_update_mask(c->core_seat.xkb_state.state,
 			      get_xkb_mod_mask(c, state->baseMods),
 			      get_xkb_mod_mask(c, state->latchedMods),
@@ -651,7 +649,8 @@
 			      0,
 			      state->group);
 
-	notify_modifiers(seat, wl_display_next_serial(c->base.wl_display));
+	notify_modifiers(&c->core_seat,
+			 wl_display_next_serial(c->base.wl_display));
 }
 #endif
 
@@ -679,7 +678,7 @@
 			      0,
 			      0,
 			      (x11_mask >> 13) & 3);
-	notify_modifiers(&c->core_seat.seat,
+	notify_modifiers(&c->core_seat,
 			 wl_display_next_serial(c->base.wl_display));
 }
 
@@ -706,35 +705,35 @@
 		break;
 	case 4:
 		if (state)
-			notify_axis(&c->core_seat.seat,
+			notify_axis(&c->core_seat,
 				      weston_compositor_get_time(),
 				      WL_POINTER_AXIS_VERTICAL_SCROLL,
 				      wl_fixed_from_int(1));
 		return;
 	case 5:
 		if (state)
-			notify_axis(&c->core_seat.seat,
+			notify_axis(&c->core_seat,
 				      weston_compositor_get_time(),
 				      WL_POINTER_AXIS_VERTICAL_SCROLL,
 				      wl_fixed_from_int(-1));
 		return;
 	case 6:
 		if (state)
-			notify_axis(&c->core_seat.seat,
+			notify_axis(&c->core_seat,
 				      weston_compositor_get_time(),
 				      WL_POINTER_AXIS_HORIZONTAL_SCROLL,
 				      wl_fixed_from_int(1));
 		return;
 	case 7:
 		if (state)
-			notify_axis(&c->core_seat.seat,
+			notify_axis(&c->core_seat,
 				      weston_compositor_get_time(),
 				      WL_POINTER_AXIS_HORIZONTAL_SCROLL,
 				      wl_fixed_from_int(-1));
 		return;
 	}
 
-	notify_button(&c->core_seat.seat,
+	notify_button(&c->core_seat,
 		      weston_compositor_get_time(), button,
 		      state ? WL_POINTER_BUTTON_STATE_PRESSED :
 			      WL_POINTER_BUTTON_STATE_RELEASED);
@@ -799,7 +798,7 @@
 				 * and fall through and handle the new
 				 * event below. */
 				update_xkb_state_from_core(c, key_release->state);
-				notify_key(&c->core_seat.seat,
+				notify_key(&c->core_seat,
 					   weston_compositor_get_time(),
 					   key_release->detail - 8,
 					   WL_KEYBOARD_KEY_STATE_RELEASED,
@@ -828,7 +827,7 @@
 			 * event, rather than with the focus event.  I'm not
 			 * sure of the exact semantics around it and whether
 			 * we can ensure that we get both? */
-			notify_keyboard_focus_in(&c->core_seat.seat, &c->keys,
+			notify_keyboard_focus_in(&c->core_seat, &c->keys,
 						 STATE_UPDATE_AUTOMATIC);
 
 			free(prev);
@@ -845,7 +844,7 @@
 			key_press = (xcb_key_press_event_t *) event;
 			if (!c->has_xkb)
 				update_xkb_state_from_core(c, key_press->state);
-			notify_key(&c->core_seat.seat,
+			notify_key(&c->core_seat,
 				   weston_compositor_get_time(),
 				   key_press->detail - 8,
 				   WL_KEYBOARD_KEY_STATE_PRESSED,
@@ -860,7 +859,7 @@
 				break;
 			}
 			key_release = (xcb_key_press_event_t *) event;
-			notify_key(&c->core_seat.seat,
+			notify_key(&c->core_seat,
 				   weston_compositor_get_time(),
 				   key_release->detail - 8,
 				   WL_KEYBOARD_KEY_STATE_RELEASED,
@@ -879,7 +878,7 @@
 			output = x11_compositor_find_output(c, motion_notify->event);
 			x = wl_fixed_from_int(output->base.x + motion_notify->event_x);
 			y = wl_fixed_from_int(output->base.y + motion_notify->event_y);
-			notify_motion(&c->core_seat.seat,
+			notify_motion(&c->core_seat,
 				      weston_compositor_get_time(), x, y);
 			break;
 
@@ -899,7 +898,7 @@
 			x = wl_fixed_from_int(output->base.x + enter_notify->event_x);
 			y = wl_fixed_from_int(output->base.y + enter_notify->event_y);
 
-			notify_pointer_focus(&c->core_seat.seat,
+			notify_pointer_focus(&c->core_seat,
 					     &output->base, x, y);
 			break;
 
@@ -910,7 +909,7 @@
 			if (!c->has_xkb)
 				update_xkb_state_from_core(c, enter_notify->state);
 			output = x11_compositor_find_output(c, enter_notify->event);
-			notify_pointer_focus(&c->core_seat.seat, NULL, 0, 0);
+			notify_pointer_focus(&c->core_seat, NULL, 0, 0);
 			break;
 
 		case XCB_CLIENT_MESSAGE:
@@ -933,7 +932,7 @@
 			if (focus_in->mode == XCB_NOTIFY_MODE_WHILE_GRABBED ||
 			    focus_in->mode == XCB_NOTIFY_MODE_UNGRAB)
 				break;
-			notify_keyboard_focus_out(&c->core_seat.seat);
+			notify_keyboard_focus_out(&c->core_seat);
 			break;
 
 		default:
@@ -959,7 +958,7 @@
 	case XCB_KEY_RELEASE:
 		key_release = (xcb_key_press_event_t *) prev;
 		update_xkb_state_from_core(c, key_release->state);
-		notify_key(&c->core_seat.seat,
+		notify_key(&c->core_seat,
 			   weston_compositor_get_time(),
 			   key_release->detail - 8,
 			   WL_KEYBOARD_KEY_STATE_RELEASED,