Use join_strings to format value_set output

Author: jezhiggins

src/analyses/variable-sensitivity/value_set_abstract_object.cpp

@@ -15,6 +15,7 @@
 #include <analyses/variable-sensitivity/interval_abstract_value.h>
 #include <analyses/variable-sensitivity/two_value_array_abstract_object.h>
 #include <analyses/variable-sensitivity/value_set_abstract_object.h>
+#include <util/string_utils.h>
 
 using abstract_object_sett = value_set_abstract_objectt::abstract_object_sett;
 
@@ -411,14 +412,8 @@ void value_set_abstract_objectt::output(
     }
     std::sort(output_values.begin(), output_values.end(), by_length);
 
-    bool comma = false;
-    for(auto const &value : output_values)
-    {
-      if(comma)
-        out << ", ";
-      out << value;
-      comma = true;
-    }
+    join_strings(out, output_values.begin(), output_values.end(), ", ");
+
     out << " :value-set-end";
   }
 }