Remove the no longer used non-API function ap_single_module_init() to make

some people happy who considers this as dead code since it's usage in mod_so
was removed.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82884 13f79535-47bb-0310-9956-ffa450edef68