Backport r1557639 r1557640 from trunk

    restore http://svn.apache.org/viewvc?view=revision&revision=233369
    under a configurable option: don't run mod_dir if r->handler is already set.

Backported by: covner
Reviewed By: jim, ylavic



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1573580 13f79535-47bb-0310-9956-ffa450edef68