Support for multiple cache files. The selecting of a cache file is done by a simple round-robin that selects
the first file in the list, and then moves it to the end. If the selected file hasn't got enough space, the next
one is tried. If no file has enough space, the LRU discarding is applied to the first file in the list.


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@1724 d4fa192b-c00b-0410-8231-f00ffab90ce4