Merge r1766160 from trunk:

mpm_unix: Apache fails to start if previously crashed then restarted with
the same PID (e.g. in container).  PR 60261.

Proposed by: Val <valentin.bremond gmail.com>
Reviewed by: ylavic

Submitted by: ylavic
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1768078 13f79535-47bb-0310-9956-ffa450edef68