Merge r395211, r410828 from trunk:

* configure.in: Add --with-included-apr flag to force use of the
bundled copies of APR and APR-util.

* configure.in: Use common variables for the required APR/APR-util
version.

Reviewed by: jorton, rpluem, pquerna


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@424693 13f79535-47bb-0310-9956-ffa450edef68