Make the error bucket a real meta-data bucket. This means that the

bucket length is 0, and a read returns NULL data.  If one of these
buckets is passed down after the headers are sent, this data will
just be ignored.
Submitted by:	Greg Stein


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87883 13f79535-47bb-0310-9956-ffa450edef68