entry_list_is_constrained() should look at the guard_selection_t object
We use entry_list_is_constrained() in a few places to find out if our list of entry points is highly limited (e.g., to a few bridges or a few EntryNodes). But it doesn't do that very well: instead, it looks to see if EntryNodes is set or UseBridges is set.
We have better ways: we should be looking at the size of the guard sample, or something.