Submits ORIGIN frame.

ORIGIN frame is a non-critical extension to HTTP/2 and defined by
`RFC 8336 <https://tools.ietf.org/html/rfc8336>`_.

The *flags* is currently ignored and should be
:enum:`nghttp2_flag.NGHTTP2_FLAG_NONE`.

The *ov* points to the array of origins.  The *nov* specifies the
number of origins included in *ov*.  This function creates copies
of all elements in *ov*.

The ORIGIN frame is only usable by a server.  If this function is
invoked with client side session, this function returns
:enum:`nghttp2_error.NGHTTP2_ERR_INVALID_STATE`.

:enum:`nghttp2_error.NGHTTP2_ERR_NOMEM`
    Out of memory
:enum:`nghttp2_error.NGHTTP2_ERR_INVALID_STATE`
    The function is called from client side session.
:enum:`nghttp2_error.NGHTTP2_ERR_INVALID_ARGUMENT`
    There are too many origins, or an origin is too large to fit
    into a default frame payload.