Fix USB serial issues printing before device ready

teensy4/usb.c

 		}
 		break;
 	  case 0x2221: // CDC_SET_CONTROL_LINE_STATE
-		//usb_cdc_line_rtsdtr_millis = systick_millis_count;
-		//usb_cdc_line_rtsdtr = setup.wValue;
+		usb_cdc_line_rtsdtr_millis = systick_millis_count;
+		usb_cdc_line_rtsdtr = setup.wValue;
 	  case 0x2321: // CDC_SEND_BREAK
 		endpoint0_receive(NULL, 0, 0);
 		return;

teensy4/usb_serial.c

 
 int usb_serial_write(const void *buffer, uint32_t size)
 {
+	if (!usb_configuration) return 0;
 	// TODO: do something so much better that this quick hack....
 	if (size > sizeof(txbuffer)) size = sizeof(txbuffer);
 	int count=0;