Make sure the DSO emulation code for HPUX finds the proprietary shl_xxx()

functions which are in libdld under HPUX 9/10.

PR: 2378


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@81521 13f79535-47bb-0310-9956-ffa450edef68