[PATCH] Add 'reverse' capability query to remote protocol (qSupported).

[Jakob Engblom]

> > [...]  it
> > would mean that anybody with a deployed target that doesn't yet
> > support the new "qSupported" probe would have to make his users
> > enable them by hand.
> >
> > (why I cc:ed Jakob and Greg.)
> 
>  From our side we're fine with it defaulting to off and we'll add support
> for new probe (we haven't released anything yet, so it's fine).

I agree that it makes sense to default to off. 

To support gdb7, we will need to update our side anyway. So there is no point in
trying to be nice. Better to fail early and fail often, as far as I am
concerned.

/jakob