bad header info: ap_rflush does not return the number of bytes flushed, it...

bad header info: ap_rflush does not return the number of bytes flushed, it returns 0 on success, -1 on error.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1368393 13f79535-47bb-0310-9956-ffa450edef68