On the 2.4.x-mod_md branch:

merged mod_md relevant parts of 1818030,1818120,1818308,1818725,1818792,1818849,1819799,1819854,1819943,1820036,1820310,1820312 from trunk


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x-mod_md@1820314 13f79535-47bb-0310-9956-ffa450edef68