Fix missing control path.

Closes #2190. Thanks to RengeRenge.

lib/options.c

@@ -270,8 +270,7 @@ int mosquitto_string_option(struct mosquitto *mosq, enum mosq_opt_t option, cons
 
 	switch(option){
 		case MOSQ_OPT_TLS_ENGINE:
-#ifdef WITH_TLS
+#if defined(WITH_TLS) && !defined(OPENSSL_NO_ENGINE)
-#    if !defined(OPENSSL_NO_ENGINE)
 			eng = ENGINE_by_id(value);
 			if(!eng){
 				return MOSQ_ERR_INVAL;
@@ -282,7 +281,6 @@ int mosquitto_string_option(struct mosquitto *mosq, enum mosq_opt_t option, cons
 				return MOSQ_ERR_NOMEM;
 			}
 			return MOSQ_ERR_SUCCESS;
-#endif
 #else
 			return MOSQ_ERR_NOT_SUPPORTED;
 #endif