[RFC] Restricting dependacies to particular platforms

[Martijn van Oosterhout <kleptog@cupid.suninternet.com>]

Over the last few weeks I've been keeping track of
the dependancies of all the packages and trying to
fix bad ones but I've come up against a bit of a 
problem.

Differing architectures sometimes have differing
package names. Sometimes package list dependancies
for packages which no longer exist in potato but did
exist within slink.

Because these dependancies are not nessesarily bad
it would be nice if these situations could be clearly
marked.

For example, all the packages using alsalib list in
their dependancies:

libasound0 | libasound0.4

libasound0 is for slink (I figure, since it's not listed
anywhere else). libasound0.4 is in potato. setiathome lists
libc6.1 because it apperantly exists on alpha.

I think we should find a way of marking these so all the
spurious warnings can be removed. Maybe:

Depends: slink:libasound | potato:libasound0.4

and

Depends: alpha:libc6.1 | !alpha:libc6

Comments?

Martijn