changed the following APIs to return an error instead of hard exiting:

ap_add_module, ap_add_loaded_module, ap_setup_prelinked_modules,
and ap_process_resource_config


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@103517 13f79535-47bb-0310-9956-ffa450edef68