core: ensure that MPMs return an error on runtime failure and hence that
      httpd's main process also exits with an error.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1629925 13f79535-47bb-0310-9956-ffa450edef68
core: follow up to r1629925: new log tag

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1629927 13f79535-47bb-0310-9956-ffa450edef68