Merge branch 'jk/http-test-cgipassauth-unavailable-in-older-apache'

We started unconditionally testing with CGIPassAuth directive but
it is unavailable in older Apache that ships with CentOS 7 that has
about a year of shelf-life still left.  The test has conditionally
been disabled when running with an ancient Apache.  This was a fix
for a recent regression caught before the release, so no need to
mention it in the release notes.

* jk/http-test-cgipassauth-unavailable-in-older-apache:
  t/lib-httpd: make CGIPassAuth support conditional

diff --cc t/lib-httpd.sh
Simple merge

diff --cc t/lib-httpd/apache.conf
Simple merge

diff --cc t/t5563-simple-http-auth.sh
Simple merge