Make SimpleCapture::stop() be able to be called multiple times and at any point so that it can be called from the destructor and an assert failure can return immediately. Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>