Bug#201023: dosemu: purging doesmu wipes out all user data

[Samium Gromoff <deepfire@ibe.miee.ru>]

> Have you actually looked in your /var/lib/dpkg/info to see how many
> packages do an unconditional rm -r in their purge code? Changing this
> piecemeal will only give users a false sense of security.

I think the issue can be addressed by a finer file classification.
It seems to me its a classical case of not-enough-information.

 1. data/exec files
 2. default/generated config files
 3. _user_modified_ config files

The whole issue seem to be caused by the fact we do not distinguish
between 2 and 3.

For instance i believe we should clearly remove 2 and keep 3.

And by the way i tend to agree with Herbert on the
false-sense-of-security thing.

regards, Samium Gromoff