* apr_brigade_partition() now returns an apr_status_t (finally!).

* did some code cleanups/optimizations in that function.
* updated Apache's byterange filter to handle the new prototype. added
  error handling to the byterange filter should apr_brigade_partition()
  ever fail, which it never will unless somebody either removes the earlier
  call to apr_brigade_length() for some unknown reason or invents a new
  bucket type that is of a predetermined length but which cannot be split
  natively (or which has a split that might fail).  might as well be
  future-proof.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89363 13f79535-47bb-0310-9956-ffa450edef68