Fix a bug where errors that happen during early request parsing (like 400

HTTP_BAD_REQUEST) don't send any error message content to the browser.
The core_filter wasn't present this early in request parsing, so the output
went into the bit bucket via r[v]puts->ap_pass_brigade.

The chunking filter takes care of itself nicely, because it is added in
ap_send_http_header if it's needed.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86253 13f79535-47bb-0310-9956-ffa450edef68