Declare only the scopes MEOS does not state

[estebanzimanyi]

A type-scope declaration stands in for a scope MEOS itself leaves unstated, so
it carries weight only while the function states nothing.

Three entries describe something else. contained_span_span and
span_to_spanset are declared empty, and nad_tcbuffer_stbox is scoped to
tcbuffer, on the grounds that each names a wrapper serving none of them. Each
names the wrapper that backs it — Contained_span_span, Span_to_spanset,
NAD_tcbuffer_stbox — and is that wrapper's only claimant, so no filtering
applies to it at all.

An empty declaration is the dangerous shape once its cause is gone: it stops
describing a function that serves none of its wrapper's overloads and starts
stripping one that serves all of them.

Regenerating against MobilityDB master leaves all 5513 functions' signature
lists unchanged, so the three carry no weight.

The t<num>box_shift_scale entries stay. Their scope derives to the span types
their bodies manipulate rather than to tbox, which their wrapper's
(tbox, integer|bigint|float) overloads do not match, so removing them costs
each of the three its whole surface.

tests/test_family.py::test_representative_symbols_land_in_their_family and
tests/test_struct_layout.py::test_core_structs_have_real_offsets fail on
master as well.