std: use #ifdef rather than #if where the constant may not be defined

diff --git a/std.c b/std.c
index 727ee6e98576e4c9c11b999820ad27f5bc3a3b68..93ca942501fd3611a43d45d553d20cfe5ad03c86 100644 (file)
--- a/std.c
+++ b/std.c
@@ -264,11 +264,11 @@ SR_PRIV int std_dev_clear(const struct sr_dev_driver *driver,
                        driver->dev_close(sdi);
 
                if (sdi->conn) {
-#if HAVE_LIBSERIALPORT
+#ifdef HAVE_LIBSERIALPORT
                        if (sdi->inst_type == SR_INST_SERIAL)
                                sr_serial_dev_inst_free(sdi->conn);
 #endif
-#if HAVE_LIBUSB_1_0
+#ifdef HAVE_LIBUSB_1_0
                        if (sdi->inst_type == SR_INST_USB)
                                sr_usb_dev_inst_free(sdi->conn);
 #endif