We have a poor abstraction in the protocol. This is a temporary

We have a poor abstraction in the protocol.  This is a temporary
hack to fix the bug, but it will need to be fixed for real.  If
we find an error while sending out a custom error response, we back
up to the first non-OK request and send the data.  Then, when we send
the EOS from finalize_request_protocol, we go to the last request,
to ensure that we aren't sending an EOS to a request that has already
received one.  Because the data is sent on a different request than
the EOS, the error text never gets sent down the filter stack.  This
fixes the problem by finding the last request, and sending the data
with that request.
PR:	7165

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88000 13f79535-47bb-0310-9956-ffa450edef68