added arduino, modified build

arduino/libraries/Ethernet/examples/LinkStatus/LinkStatus.ino

@@ -0,0 +1,43 @@
+/*
+  Link Status
+  This sketch prints the ethernet link status. When the
+  ethernet cable is connected the link status should go to "ON".
+  NOTE: Only WizNet W5200 and W5500 are capable of reporting
+  the link status. W5100 will report "Unknown".
+  Hardware:
+   - Ethernet shield or equivalent board/shield with WizNet 5200/5500
+  Written by Cristian Maglie
+  This example is public domain.
+*/
+
+#include <SPI.h>
+#include <Ethernet.h>
+
+void setup() {
+  // You can use Ethernet.init(pin) to configure the CS pin
+  //Ethernet.init(10);  // Most Arduino shields
+  //Ethernet.init(5);   // MKR ETH shield
+  //Ethernet.init(0);   // Teensy 2.0
+  //Ethernet.init(20);  // Teensy++ 2.0
+  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
+  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet
+
+  Serial.begin(9600);
+}
+
+void loop() {
+  auto link = Ethernet.linkStatus();
+  Serial.print("Link status: ");
+  switch (link) {
+    case Unknown:
+      Serial.println("Unknown");
+      break;
+    case LinkON:
+      Serial.println("ON");
+      break;
+    case LinkOFF:
+      Serial.println("OFF");
+      break;
+  }
+  delay(1000);
+}