Only close hdrs.fd when returning non-OK from cache_select(),

because it will be read from in the very next mod_cache callback
recall_headers().  Problem masked on unix by buffering.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1547845 13f79535-47bb-0310-9956-ffa450edef68