Merge r384580, r390210 and r390619 from trunk, changing the flushing band-aid...

Merge r384580, r390210 and r390619 from trunk, changing the flushing band-aid in mod_proxy_ajp to be configurable.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@390728 13f79535-47bb-0310-9956-ffa450edef68