Changes with Apache 2.4.20

  *) core: Do not read .htaccess if AllowOverride and AllowOverrideList
    are "None". PR 58528.

  *) mod_proxy_express: Fix possible use of DB handle after close.  PR 59230.

  *) core/util_script: relax alphanumeric filter of enviroment variable names
    on Windows to allow '(' and ')' for passing PROGRAMFILES(X86) et.al.
    unadulterated in 64 bit versions of Windows. PR 46751.

  *) mod_http2: incrementing keepalives on each request started so that logging
    %k gives increasing numbers per master http2 connection.
    New documented variables in env, usable in custom log formats: H2_PUSH,
    H2_PUSHED, H2_PUSHED_ON, H2_STREAM_ID and H2_STREAM_TAG.

  *) mod_http2: more efficient passing of response bodies with less contention
    and file bucket forwarding.

  *) mod_http2: fix for missing score board updates on request count, fix for
    memory leak on slave connection reuse.

  *) mod_http2: Fix build on Windows from dsp files.

(adam)