Fix the first bucket not getting chunked properly. The reason was that

Fix the first bucket not getting chunked properly.  The reason was that
we left the TE header in the output headers, so ap_set_keepalive didn't
set r->chunked to 1.  So, ap_http_header_filter wouldn't insert CHUNK
filter appropriately.  I have no clue how it chunked anything at all
before this patch, but hey, it looks right now.

Tested with Yahoo, Apple, apache.org, and /.
/. is interesting in that it sends both Conn: Close and TE: chunked.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91463 13f79535-47bb-0310-9956-ffa450edef68