Merge r1599486 from trunk

mod_proxy_http: Avoid (unlikely) access to freed memory.

Submitted by: ylavic
Reviewed by: ylavic, jorton, rjung
Backported by: jailletc36

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1632736 13f79535-47bb-0310-9956-ffa450edef68