apache24: updated to 2.4.39

Changes with Apache 2.4.39

*) mod_proxy/ssl: Cleanup per-request SSL configuration anytime a backend
  connection is recycled/reused to avoid a possible crash with some SSLProxy
  configurations in <Location> or <Proxy> context.

*) mod_ssl: Correctly restore SSL verify state after TLSv1.3 PHA failure.

*) mod_log_config: Support %{c}h for conn-hostname, %h for useragent_host

*) mod_socache_redis: Support for Redis as socache storage provider.

*) core: new configuration option 'MergeSlashes on|off' that controls handling of
  multiple, consecutive slash ('/') characters in the path component of the request URL.

*) mod_http2: when SSL renegotiation is inhibited and a 403 ErrorDocument is
  in play, the proper HTTP/2 stream reset did not trigger with H2_ERR_HTTP_1_1_REQUIRED.

*) mod_http2: new configuration directive: `H2Padding numbits` to control
  padding of HTTP/2 payload frames. 'numbits' is a number from 0-8,
  controlling the range of padding bytes added to a frame. The actual number
  added is chosen randomly per frame. This applies to HEADERS, DATA and PUSH_PROMISE
  frames equally. The default continues to be 0, e.g. no padding.

*) mod_http2: ripping out all the h2_req_engine internal features now that mod_proxy_http2
  has no more need for it. Optional functions are still declared but no longer implemented.
  While previous mod_proxy_http2 will work with this, it is recommeneded to run the matching
  versions of both modules.

*) mod_proxy_http2: changed mod_proxy_http2 implementation and fixed several bugs which
  resolve bug 63170. The proxy module does now a single h2 request on the (reused)
  connection and returns.

*) mod_http2/mod_proxy_http2: proxy_http2 checks correct master connection aborted status
  to trigger immediate shutdown of backend connections. This is now always signalled
  by mod_http2 when the the session is being released.
  proxy_http2 now only sends a PING frame to the backend when there is not already one
  in flight.

*) mod_proxy_http2: fixed an issue where a proxy_http2 handler entered an infinite
  loop when encountering certain errors on the backend connection.

*) mod_http2: Configuration directives H2Push and H2Upgrade can now be specified per
  Location/Directory, e.g. disabling PUSH for a specific set of resources.

*) mod_http2: HEAD requests to some module such as mod_cgid caused the stream to
  terminate improperly and cause a HTTP/2 PROTOCOL_ERROR.

*) http: Fix possible empty response with mod_ratelimit for HEAD requests.

*) mod_cache_socache: Avoid reallocations and be safe with outgoing data
  lifetime.

*) MPMs unix: bind the bucket number of each child to its slot number, for a
  more efficient per bucket maintenance.

*) mod_auth_digest: Fix a race condition. Authentication with valid
  credentials could be refused in case of concurrent accesses from
  different users.

*) mod_http2: enable re-use of slave connections again. Fixed slave connection
  keepalives counter.

*) mod_reqtimeout: Allow to configure (TLS-)handshake timeouts.

*) mod_proxy_wstunnel: Fix websocket proxy over UDS.

*) mod_ssl: Don't unset FIPS mode on restart unless it's forced by
  configuration (SSLFIPS on) and not active by default in OpenSSL.

(adam)