Changes

completion/lstopo: update the list of output formats

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

lstopo: if stdout is redirected, use console mode

Except if tcgetpgrp(STDIN) fails, we're likely launched by a
window manager outside of a terminal in this case.

Closes #503

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

lstopo: only show interactive help if stdout is a tty

Otherwise things like .xsession-errors (depending on the window manager)
might get flooded with those messages.

Ignored on Windows since I have now idea where those messages go
when the app doesn't run from a terminal.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

lstopo: add an explicit "window" output format

To force the graphical window output in case we're
using console for some reason.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>