add HOST and PORT to feed cache key

feed.php

@@ -21,7 +21,7 @@ $opt = rss_parseOptions();
 // the feed is dynamic - we need a cache for each combo
 // (but most people just use the default feed so it's still effective)
 $cache = getCacheName(join('', array_values($opt)).$_SERVER['REMOTE_USER'], '.feed');
-$key   = join('', array_values($opt)).$_SERVER['REMOTE_USER'];
+$key   = join('', array_values($opt)).$_SERVER['REMOTE_USER'].$_SERVER['HTTP_HOST'].$_SERVER['SERVER_PORT'];
 $cache = new cache($key, '.feed');
 
 // prepare cache depends