QUIC: stateless retry. Previously, quic connection object was created when Retry packet was sent. This is neither necessary nor convenient, and contradicts the idea of retry: protecting from bad clients and saving server resources. Now, the connection is not created, token is verified cryptographically instead of holding it in connection.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


have=NGX_SUPPRESS_WARN . auto/have

have=NGX_SMP . auto/have