Progress on capabilities

Capabilities will be shared among collection of threads. A pager
will have a right to share its own capabilities with its space,
its thread group and its container.

Currently sharing is possible with only all of the caps. Next,
it will be support for cap splitting, granting, and partial sharing
and granting.

src/generic/space.c

@@ -107,6 +107,7 @@ struct address_space *address_space_create(struct address_space *orig)
 
 	/* Initialize space structure */
 	link_init(&space->list);
+	cap_list_init(&space->cap_list);
 	mutex_init(&space->lock);
 	space->pgd = pgd;