core: fix ap_request_core_filter()'s brigade lifetime.

core: fix ap_request_core_filter()'s brigade lifetime.

The filter should pass everything up to and including EOR, then bail out.
For EOR it can't use a brigade created on r->pool, so retain one created
on c->pool in c->notes (this avoids leaking a brigades for each request
on the same connection).

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1822596 13f79535-47bb-0310-9956-ffa450edef68