Access `skip` from its owning module

[nickrobinson251]

Noticed when running ExplicitImports.jl on a module with PB generated files. Got:

Module `Foo.Rel` has qualified accesses to names via modules other than their owner as determined via `Base.which`:
- `skip` has owner `Base` but it was accessed from `ProtoBuf` at `~/Foo/src/Rel/Rel_pb.jl:1019:16`