configure: Move the --with-included-apr check so that srcdir!=builddir builds

aren't broken by it.

Backport of r1232838 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1238400 13f79535-47bb-0310-9956-ffa450edef68