Use SysV semaphores by default on OpenBSD.

Submitted by:	Henning Brauer <hb-apache-dev@bsws.de>
Reviewed by:	Jim Jagielski, Jeff Trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@96096 13f79535-47bb-0310-9956-ffa450edef68