Avoid compile error.

"a label can only be part of a statement and a declaration is not a
statement"

plugins/persist-sqlite/base_msgs.c

@@ -84,6 +84,7 @@ static char *properties_to_json(const mosquitto_property *properties)
 				break;
 
 			case MQTT_PROP_CORRELATION_DATA:
+				{
 					/* bin */
 					void *binval = NULL;
 					mosquitto_property_read_binary(properties, propid, &binval, &len, false);
@@ -105,6 +106,7 @@ static char *properties_to_json(const mosquitto_property *properties)
 						return NULL;
 					}
 					free(hexval);
+				}
 				break;
 
 			case MQTT_PROP_USER_PROPERTY: