Remove default axiom in associate array to pointer

These default axioms are not useful, as constraints are already added on
input strings and fresh strings.
This also moves default axoims from associate_char_array_of_pointer to
char_array_of_pointer, because the first function will be pulled out of
the class.

Author: romainbrenguier

src/solvers/refinement/string_constraint_generator_main.cpp

@@ -249,7 +249,6 @@ string_constraint_generatort::associate_char_array_to_char_pointer(
   auto insert_result =
     arrays_of_pointers_.insert(std::make_pair(char_pointer, array_sym));
   array_string_exprt result = to_array_string_expr(insert_result.first->second);
-  add_default_axioms(result);
   return result;
 }
 
@@ -410,6 +409,7 @@ array_string_exprt string_constraint_generatort::char_array_of_pointer(
   const array_typet array_type(pointer.type().subtype(), length);
   const array_string_exprt array =
     associate_char_array_to_char_pointer(pointer, array_type);
+  add_default_axioms(array);
   return array;
 }