Consider a module and one of its buildtime dependencies.

If that dependency declares a filter, the packages in that filter should be made non-installable in the buildroot at buildtime for our topmost module.

An easy way to do this would be to add the list of packages from all of the deps' filters as Conflicts in the srpm macros package.

• Those conflicts should be exact NVRs of the binary rpms from the module. We don't want a Conflict declaration from one dep to interfere with content we really want from a second dep.
• This should also extend to the transitive dependencies, from #530.