[mingw32] stdin redirection

[Eli Zaretskii]

> Date: Thu, 12 Apr 2007 18:47:44 +0200
> From: Joel Brobecker <brobecker@adacore.com>
> 
> > > If we could find a way to replace the current implementation of
> > > fd_is_pipe into something that avoids using any of the pipe functions,
> > > then that would probably solve our problem. Unfortunately, despite
> > > our intensive search of MSDN, nothing turned up.
> > 
> > To the best of my knowledge there is no way.
> 
> That's what we though too :-(.

Can't we maintain a list of all file descriptors used by GDB, where
those which are open on a pipe are marked as such?  Then we'd _know_
what API with each fd to use without relying on dysfunctional tests.