First part to fix the synchronization-locking for RewriteMap programs under

Unix derivates who doesn't accept the locking of pipes directly.

But we perhaps have another problem: According to FreeBSD's manpage and a hint
by the submitter of PR#1029 flock() has to be used on opened filedescriptors
which are _not_ duplicated via fork().  This currently is not the case...

Submitted by: Ralf S. Engelschall
Reviewed by: Ralf S. Engelschall, Jim Jagielski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@80311 13f79535-47bb-0310-9956-ffa450edef68