Change AP_MIN_BYTES_TO_WRITE from 9000 to 8192 to match the bucket buffer

size.  This fixes the 8192-808-8192-808 iovec-length sequence problem
on platforms using writev() (eg OS/2).

Reviewed by:	Brian Havard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88843 13f79535-47bb-0310-9956-ffa450edef68