Pre-commit a simple bit from r219224, pass an initialized input_brigade
  off to the spool/stream functions.  Effectively a no-op so far, but in
  a couple of patches, the reason becomes obvious.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/proxy-reqbody-2.0.x@230714 13f79535-47bb-0310-9956-ffa450edef68