(Analyze_generic_subprogram_Declaration): Set outer_generic_scope,
to prevent freezing within formal packages.
(Freeze_Subprogram_Body): If body comes from another instance that
appeared before its own body, place freeze node at end of current
declarative part, to prevent a back-end crash.
(Inline_Instance_Body): Handle properly a package instance within
a subprogram instance that is a child unit.