Create Files, and thus MMAPs, out of the request pool, not the

Create Files, and thus MMAPs, out of the request pool, not the
connection pool.  This solves a small resource leak that had us
not closing files until a connection was closed.  In order to do
this, at the end of the core_output_filter, we loop through the
brigade and convert any data we have into a single HEAP bucket
that we know will survive clearing the request_rec.

Submitted by:	Ryan Bloom, Justin Erenkrantz <jerenkrantz@ebuilt.com>,
                Cliff Woolley

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88964 13f79535-47bb-0310-9956-ffa450edef68