Add allow_oversubscribe kernel argument

It's not allowed in the default setting.
Execute mcreboot.sh with -O option to allow it.

refs #1072

kernel/include/process.h

@@ -278,6 +278,7 @@ struct resource_set {
 extern struct list_head	resource_set_list;
 extern mcs_rwlock_lock_t	resource_set_lock;
 extern int idle_halt;
+extern int allow_oversubscribe;
 
 struct process_hash {
 	struct list_head	list[HASH_SIZE];