[openssl/openssl] 56e303: Ignore retry packets that arrive too late

[Matt Caswell]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 56e303259ed48884c914fe24b354e9cc7b7532c3
      https://github.com/openssl/openssl/commit/56e303259ed48884c914fe24b354e9cc7b7532c3
  Author: Matt Caswell <matt at openssl.org>
  Date:   2023-10-19 (Thu, 19 Oct 2023)

  Changed paths:
    M ssl/quic/quic_channel.c

  Log Message:
  -----------
  Ignore retry packets that arrive too late

RFC 9000 s 17.2.5.2 says

> After the client has received and processed an Initial or Retry packet
> from the server, it MUST discard any subsequent Retry packets that it
> receives.

We were checking for multiple Retry packets, but not if we had already
processed an Initial packet.

Fixes the assertion failure noted in
https://github.com/openssl/openssl/pull/22368#issuecomment-1765618884

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22411)