kernel: implement globally-unique object ids

include/kernel/object.h

@@ -3,8 +3,8 @@
 
 #include <kernel/flags.h>
 #include <kernel/locks.h>
-#include <mango/status.h>
 #include <kernel/vm.h>
+#include <mango/status.h>
 #include <stddef.h>
 
 #ifdef __cplusplus
@@ -67,6 +67,7 @@ struct object_type {
 
 struct object {
 	uint32_t ob_magic;
+	koid_t ob_id;
 	struct object_type *ob_type;
 	spin_lock_t ob_lock;
 	unsigned int ob_refcount;