Don't call `h2o_http2_conn_request_write` from `emit_writereq_of_openref`
This fixes an issue seen when 'server-timing: enforced' is set in the
configuration: proceed would set the write callback, and we'd hit the
assert in `do_emit_writereq()` checking that `buf_in_flight` is `NULL`:
```
h2o: lib/http2/connection.c:1229: do_emit_writereq: Assertion `conn->_write.buf_in_flight == NULL' failed.
```
@@ -1216,7 +1216,6 @@ static int emit_writereq_of_openref(h2o_http2_scheduler_openref_t *ref, int *sti
}
h2o_hpack_flatten_trailers(&conn->_write.buf, &conn->_output_header_table, stream->stream_id,
conn->peer_settings.max_frame_size, trailers, num_trailers);
- h2o_http2_conn_request_write(conn);
}
h2o_linklist_insert(&conn->_write.streams_to_proceed, &stream->_refs.link);
}
