swap_prefetch: add NR_ANON

Separated out by request from Andrew.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.17-rc6-cl/mm/swap_prefetch.c
===================================================================
--- linux-2.6.17-rc6-cl.orig/mm/swap_prefetch.c	2006-06-10 14:57:06.644921771 -0700
+++ linux-2.6.17-rc6-cl/mm/swap_prefetch.c	2006-06-10 15:39:44.582122436 -0700
@@ -395,6 +395,7 @@ static int prefetch_suitable(void)
 		 * would be expensive to fix and not of great significance.
 		 */
 		limit = node_page_state(node, NR_MAPPED) +
+			node_page_state(node, NR_ANON) +
 			ps.nr_slab + ps.nr_dirty +
 			ps.nr_unstable + total_swapcache_pages;
 		if (limit > ns->prefetch_watermark) {