Inject a specialization of std::hash<> for the V4L2PixelFormat class in the std namespace to make it possible to store instances of the class in the std::unordered_map and std::unordered_set containers. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> Tested-by: Paul Elder <paul.elder@ideasonboard.com>