Make sure the argument for the --add-module option to APACI's configure script

is of type [path/to/]mod_xxx.c because all calculations inside configure and
src/Configure depend on this.

PR: 2307


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@81406 13f79535-47bb-0310-9956-ffa450edef68