Incremental SMT2: support cast from pointer to integer of different width

Do a zero extension, just like the propositional back-end does.

Author: tautschnig

src/solvers/smt2_incremental/convert_expr_to_smt.cpp

@@ -165,6 +165,8 @@ extension_for_type(const typet &type)
     return smt_bit_vector_theoryt::zero_extend;
   if(can_cast_type<bv_typet>(type))
     return smt_bit_vector_theoryt::zero_extend;
+  if(can_cast_type<pointer_typet>(type))
+    return smt_bit_vector_theoryt::zero_extend;
   UNREACHABLE;
 }