sendfile_nonblocking() takes the _brigade_ as an argument, gets

the first bucket from the brigade, finds it not to be a FILE
bucket and barfs. The fix is to pass a bucket rather than a brigade.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@462580 13f79535-47bb-0310-9956-ffa450edef68