libio? Another related question

[Thomas Riley]

I am trying to compile some stuff that wants to use 
vfscanf.
compiles go OK, but linking finds unresolved references. 

As nearly as I can tell, it should be in libio.a . 

 
Where can it be found?
 
The source in libio.tar.bz2 from
sourceware.cygnus.com/pub/cygwin/cygwin-b20/src-by-top-dir has 
nothing
to indicate that this has ever been compiled under 
cygwin.