Add dummy 86Box Unit Tester device

src/86box.c

@@ -65,6 +65,7 @@
 #include <86box/machine.h>
 #include <86box/bugger.h>
 #include <86box/postcard.h>
+#include <86box/unittester.h>
 #include <86box/isamem.h>
 #include <86box/isartc.h>
 #include <86box/lpt.h>
@@ -1222,6 +1223,8 @@ pc_reset_hard_init(void)
         device_add(&bugger_device);
     if (postcard_enabled)
         device_add(&postcard_device);
+    if (unittester_enabled)
+        device_add(&unittester_device);
 
     if (IS_ARCH(machine, MACHINE_BUS_PCI)) {
         pci_register_cards();