[mingw32] stdin redirection

[Joel Brobecker]

Daniel,

thanks for your help, by the way. I was in the process of writing
a point-by-point reply to your message, but something occured to me.
Is it normal that we're using the "terminal" serial_ops object?
I wonder whether you might be thinking that we're using the "pipe"
one, whereas I suspect the latter is only used when using "target
remote |".

I'm rebuilding GDB as we speak, to confirm that we did run the test
where fd_is_pipe would normally return 0 (basically, the case when
we're inside a cygwin "terminal"). More info soon.

-- 
Joel