Backport of Justin and Jeff's fixes to allow apxs to work with an out of tree

apr and apr-util.
Reviewed by: jerenkrantz, trawick, gstein, me


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99986 13f79535-47bb-0310-9956-ffa450edef68