* configure.in: Disallow use of bundled APR with external APR-util, or

bundled APR-util with external APR, another cause of the dreaded
PR21718.

Reviewed by: jorton, nd, trawick, pquerna


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@171097 13f79535-47bb-0310-9956-ffa450edef68