io error fixed
Fixed a wait() bug.

When a task running in the forbidden state calls the Wait() function,
directly or indirectly, it implies a temporary exit from its forbidden
state. Since almost all stdio, device I/O, and file I/O functions must
Wait() for I/O completion, performing such calls will cause your task to
Wait(), temporarily breaking the forbid.  While the task is waiting, the
system will perform normally.
Merge remote-tracking branch 'origin/master' into develop.virtio