Fix the mod_dir/mod_negotiation bug, where redirects and sub requests

Fix the mod_dir/mod_negotiation bug, where redirects and sub requests
were not getting the correct filters.  This is done by creating a location
in the request rec that holds protocol level filters.  Protocol level
filters survive for one request, from the time the request is received
from the user to the time the response is sent.  r->output_filters now
stores the request level filters, which are only valid for the lifetime
of one request_rec.

This patch works, but it is not complete.  The second half of the problem
is that add_any_filter doesn't check where it puts the filters that it
adds, so it is possible for filters to be put on this wrong list, and
for filters to be lost completely during request processing.  That half
of the fix will be coming in the next day or so.

Submitted by:	Will Rowe, Justin Erenkrantz, Ryan Bloom

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@93682 13f79535-47bb-0310-9956-ffa450edef68