[xl32]

• A CONNECT request has no :path. The worker did not set r->uri, and the location walk read a NULL pointer, so the child process stopped. Use the authority as the target, as HTTP/1.1 does.
• The worker wrote session->wake after it decremented active_tasks. At zero, the event thread can free the session. Wake first.
• Removing the last entry of a QUIC accept queue with more than one entry set the tail to NULL. The next entry replaced the head, and the queued streams or connections were lost. Keep the previous entry as the tail.
• During a graceful stop, new connections stayed in the engine until the child stopped. Free them.

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• This PR does not report or address a security vulnerability
  (see SECURITY.md and
  https://www.apache.org/security/#reporting-a-vulnerability).
  trunk only, mod_http3 never published in 2.4.x
• Code follows the httpd style guide.
• New log messages (level debug or higher) use an empty APLOGNO() tag;
  numbers are assigned by a committer at merge time (see docs/log-message-tags/README).
• If the change is user-visible, a changes-entries/*.txt file is included,
  following the template in README.CHANGES (not needed otherwise).
• Test cases based on pyhttpd are included where appropriate, in the
  test/modules/xxx directory matching the modules/xxx module source,
  or test/modules/core for core server changes. On Unix, verify these
  pass locally with e.g. make check-pytest PYTEST_DIRS=test/modules/xxx.