void nghttp2_option_set_user_recv_extension_type(nghttp2_option *option, uint8_t type)
Sets extension frame type the application is willing to handle with user defined callbacks (see
nghttp2_unpack_extension_callback). The type is extension frame type, and must be strictly greater than 0x9. Otherwise, this function does nothing. The application can call this function multiple times to set more than one frame type to receive. The application does not have to call this function if it just sends extension frames.