ap_http_header_filter() can't remove itself until after we the

CHUNK filter has been added.  Otherwise, f->next won't be the
CHUNK filter and thus the first brigade won't be chunked
properly.
Reported by:	wrowe


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86799 13f79535-47bb-0310-9956-ffa450edef68