Merge r629456 from trunk:

* Set aside buckets that remain unprocessed in the filter context for the
  next filter pass.

PR: 44447
Submitted by: Harald Niesche <harald brokenerror.de>
Reviewed by: rpluem

Submitted by: rpluem
Reviewed by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@637902 13f79535-47bb-0310-9956-ffa450edef68