Return error on bad service parameter alteration

When a service parameter is being altered and it is not in the list of
dynamic parameters, the alteration function returns an error.

server/core/config_runtime.cc

@@ -1458,6 +1458,11 @@ bool runtime_alter_service_from_json(SERVICE* service, json_t* new_json)
                         rval = false;
                     }
                 }
+                else
+                {
+                    runtime_error("Parameter '%s' cannot be modified", key);
+                    rval = false;
+                }
             }
         }
     }