Applied patch by Rene Gollent:

* Add a cached_pages field to the system_info structure, and change the
  meaning of the used_pages field to not include cached pages.
* Provide the needed info using the new calls vm_get_available_memory(),
  and vm_page_num_available_pages().


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24571 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/vm_page.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2007, Axel Dörfler, [email protected].
+ * Copyright 2002-2008, Axel Dörfler, [email protected].
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
@@ -33,6 +33,7 @@ void vm_page_requeue(struct vm_page *page, bool tail);
 // get some data about the number of pages in the system
 size_t vm_page_num_pages(void);
 size_t vm_page_num_free_pages(void);
+size_t vm_page_num_available_pages(void);
 
 status_t vm_page_write_modified_pages(struct vm_cache *cache, bool fsReenter);
 void vm_page_schedule_write_page(struct vm_page *page);