Greatly simplify the ap_http_filter logic, by using the

apr_brigade_partition function.  This should also remove a warning from
the Windows build, because apr_off_t and apr_size_t aren't the same
size.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89997 13f79535-47bb-0310-9956-ffa450edef68