ETHER: Minor adjustments for building on the simh 3.x codebase

sim_ether.h

@@ -381,6 +381,11 @@ t_stat ethq_destroy(ETH_QUE* que);                      /* release FIFO queue */
 const char *eth_capabilities(void);
 t_stat sim_ether_test (DEVICE *dptr);                   /* unit test routine */
 
+#if !defined(SIM_TEST_INIT)    	/* Need stubs for test APIs */
+#define SIM_TEST_INIT
+#define SIM_TEST(xxx)
+#endif
+
 #ifdef  __cplusplus
 }
 #endif