Signals the session so that the connection should be terminated.

The last stream ID is the minimum value between the stream ID of a
stream for which :type:`nghttp2_on_frame_recv_callback` was called
most recently and the last stream ID we have sent to the peer
previously.

The *error_code* is the error code of this GOAWAY frame.  The
pre-defined error code is one of :enum:`nghttp2_error_code`.

After the transmission, both `nghttp2_session_want_read()` and
`nghttp2_session_want_write()` return 0.

This function should be called when the connection should be
terminated after sending GOAWAY.  If the remaining streams should
be processed after GOAWAY, use `nghttp2_submit_goaway()` instead.

This function returns 0 if it succeeds, or one of the following
negative error codes:

:enum:`nghttp2_error.NGHTTP2_ERR_NOMEM`
    Out of memory.