Seed SpecConstr based on *local* calls as well as *RHS* calls.
See Note [Seeding top-level recursive groups].  The change here
is mentioned here:

   NB: before Apr 15 we used (a) only, but Dimitrios had an example
       where (b) was  crucial, so I added that.

This is a pretty small change, requested by Dimitrios, that adds
SpecConstr call patterns from the rest of the module, as well as ones
from the RHS.

Still to come: #10346.