[scponly] new patch: makes rsync work

[Péter Szabó]

> Although this should work, I would prefer to only explicitely allow
> the ones
> that we know safe -- in this case '--server' and '--sender'. Using
> getopt_long we could have a list of allowed args that we could
> validate in
> its entirety.

I like your solution: clearly it is better to implement it instead of my
patch in the long run. The reason why I didn't go on the getopt_long way
myself was that it required a substantial rewrite in several files,
which would result in a complicated patch.