Bug#560174: scilab: sivp from stable cannot be removed

[Sylvestre Ledru]

> scilab still recommends sivp, which does exist in stable release and thus
> is installed on testing+stable setups with scilab. However, sivp from
> stable is not purgeable (or removable) without hacking its prerm script.
> 
> So, please drop the sivp recommendation (sivp was removed from testing).
Sorry, I though I did it ...
I will upload it very soon.

Sylvestre