Make sure under ELF-based NetBSD (now) and OpenBSD (future) we don't search

for an underscore on dlsym() (as it's already the case for FreeBSD 3.0).

Submitted by: Todd Vierling <tv@pobox.com>
Reviewed by: Ralf S. Engelschall
PR: 2462


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82580 13f79535-47bb-0310-9956-ffa450edef68