Review ait::initialize(goto_{programt,functiont})

[tautschnig]

ait has both void initialize(const goto_programt &); and void initialize(const goto_functionst::goto_functiont &);, where goto_functiont has very little additional information. This API should be reviewed so as the enable removal of goto_programt::get_function_id which currently has a single use case in dependence_grapht::initialize.

[peterschrammel]

goto_functiont should be made aware of its own name to actually add value and simplify interfaces.

[martin-cs]

I don't see a problem here.