assign dummy value to operand for single-byte case to avoid warning.

main.c

@@ -82,6 +82,7 @@ void trace_inst (addr_t addr)
       switch(ip->nb)
 	{
 	case 1:
+	  operand = 0;  /* only to avoid "may be used unitialized" warning */
 	  break;
 	case 2:
 	  operand = getbyte(addr);

print.c

@@ -161,6 +161,8 @@ int print_inst(addr_t addr)
 
 	switch(ip->nb) {
 		case 1:
+			operand = 0;  /* only to avoid "may be used
+					 unitialized" warning */
 			break;
 		case 2:
 			operand = getbyte(addr);