Merge r1643825 from trunk:

* core: Fix -D[efined] or <Define>[d] variables lifetime accross restarts. 
        PR 57328.

Submitted-by: Armin Abfalterer <a.abfalterer gmail.com>
Reviewed/Committed-by: ylavic

Submitted by: ylavic
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1651084 13f79535-47bb-0310-9956-ffa450edef68