Add a FileDescriptor constructor that takes a UniqueFD, transfering ownership of the file descriptor to the FileDescriptor. Signed-off-by: Hirokazu Honda <hiroh@chromium.org> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Hirokazu Honda <hiroh@chromium.org> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>