Removed linux linked list dependency.

tasks/libmem/memcache/memcache.c

@@ -185,7 +185,7 @@ struct mem_cache *mem_cache_init(void *start,
 		area_start = addr_aligned;
 	}
 
-	INIT_LIST_HEAD(&cache->list);
+	link_init(&cache->list);
 	cache->start = area_start;
 	cache->end = area_start + cache_size;
 	cache->total = total;

tasks/libmem/memcache/memcache.h

@@ -17,7 +17,7 @@
  * fixed-size memory cache) Keeps track of free/occupied items within its
  * start/end boundaries. Does not grow/shrink but you can link-list it. */
 struct mem_cache {
-	struct list_head list;
+	struct link list;
 	int total;
 	int free;
 	unsigned int start;