re-introduce mod/allmodules.xml*

The change is mainly intended to save some memory during the build process.
Additionally we may get a bit more clearness in our document structure ...


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99335 13f79535-47bb-0310-9956-ffa450edef68