The Extensible constructor takes a pointer to a Private instance, whose
lifetime it then manages. Make this explicit in the API by passing the
pointer as a std::unique_ptr<Private>.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>