mod_buffer: Optional support for buffering of the input and output

filter stacks. Can collapse many small buckets into fewer larger
buckets, and prevents excessively small chunks being sent over
the wire.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@717867 13f79535-47bb-0310-9956-ffa450edef68