input: Unlink saved kbd focus listener when releasing seat

Not doing this would leave a invalid list item in the view's destroy
signal listener list if destroying a seat that had previously lost
keyboard focus.

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
diff --git a/src/input.c b/src/input.c
index 157066c..3f93e55 100644
--- a/src/input.c
+++ b/src/input.c
@@ -2194,6 +2194,9 @@
 {
 	wl_list_remove(&seat->link);
 
+	if (seat->saved_kbd_focus)
+		wl_list_remove(&seat->saved_kbd_focus_listener.link);
+
 	if (seat->pointer)
 		weston_pointer_destroy(seat->pointer);
 	if (seat->keyboard)