Backport:

mod_cache_disk: Remove the unnecessary intermediate brigade while
writing to disk. Fixes a problem where mod_disk_cache was leaving 
buckets in the intermediate brigade and not passing them to out on 
exit.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1204102 13f79535-47bb-0310-9956-ffa450edef68