V3 PATCH: Include libio.h where required

[Benjamin Kosnik]

> OK.  
> 
> Can you explain why it is wrong?

the whole point of that interface is so that libio won't be used. 
Including libio.h is against the expressed purpose of this file. 

there must be something else wrong, I'm not quite sure what. 
Perhaps you can start by looking for where the references you were 
seeing to libio-isms came in: that's probably the bug.

I'm in sunnyvale today and won't be able to look at it till later, I'm afraid.

-benjamin