The sfds code blindly uses _get_osfhandle on values that may be file
descriptors, sockets or io handles. Under visual studio, _get_osfhandle
will call the invalid parameter handler for items that are not file
descriptors. Adding the handler allows us to call this in the same way
that mingw does. We will still get an assertion, but a prior change
sends those to stdiout instead of making the user click through a
dialog.
pty and tty support was not enabled or working in the code. Without pty
support, ssh client was very non functional - e.g. openssh linux server
prompt would not come through. Now ssh client works much better in
interactive mode ( uses pty).
