Log Message:
Update to 1.4.66. From the changelog:

* [core] h2: optim: send window update in 16k units
* [mod_magnet] reset for http-response-send-file
* [multiple] fix json encoding
* [core] buffer_append_bs_escaped_json()
* [autoconf] update ax_prog_cc_for_build.m4
* [doc] add libdeflate to INSTALL
* [mod_webdav] cold func if xml reqbody w/o db conf
* [mod_webdav] check reqbody Content-Type is XML
* [doc] more consistent use of vars in examples
* [core] do not load indexfile, dirlisting if unused
* [mod_dirlisting] send ETag, Cache-Control w/ cache
* [mod_openssl] compile compat w/ openssl < 1.1.0
* [mod_webdav] webdav_reqbody_type_xml() fixes
* [core] clarify server.username = "root" error msg
* [mod_wolfssl] compat with older wolfssl versions
* [core] fix li_base64_dec() on whitespace
* [core] perf tweak buffer_eq_icase_ssn()
* [mod_deflate] fix use of libdeflate for files>128k (fixes #3161)
* [core] fix buffer_substr_replace() extend (fixes #3160)
* [mod_webdav] build with Android NDK
* [core] check r->http_status before handling Range
* [core] preprocessor option to force crypto lib
* [core] fix SIGUSR1 graceful restart w/ TLS (fixes #3164)
* [mod_authn_gssapi] warn if no confidentiality flag (fixes #3163)
* [mod_wstunnel] fix crash with bad hybivers (fixes #3165)
* [core] perf: adjust max h2 stream send increment
* [core] fix HTTP/2 downloads >= 4GiB (fixes #3166)