Remove unused function

Author: Owen Jones

src/pointer-analysis/external_value_set_expr.h

@@ -159,25 +159,6 @@ class external_value_set_exprt:public exprt
     return reinterpret_cast<const access_path_entriest &>(op1().operands());
   }
 
-  std::string get_access_path_label() const
-  {
-    switch(get_external_value_set_type())
-    {
-    case external_value_set_typet::PER_FIELD:
-      return "external_objects";
-    case external_value_set_typet::PRECISE:
-    {
-      std::ostringstream ret;
-      ret << id2string(label().get_value());
-      for(const access_path_entry_exprt &entry : access_path_entries())
-        ret << id2string(entry.label());
-      return ret.str();
-    }
-    default:
-      UNREACHABLE;
-    }
-  }
-
   std::string type_to_basename(const typet &type) const
   {
     if(type.id()!=ID_struct)