Make LinkProperties comparable.

Add equals() and hashcode() to LinkProperties and related fields.

Bug:3501569
Change-Id: Ifa737a67c16867ac43cf76bf618a483e612a189e

core/java/android/net/ProxyProperties.java

@@ -163,6 +163,16 @@ public class ProxyProperties implements Parcelable {
         return 0;
     }
 
+    @Override
+    /*
+     * generate hashcode based on significant fields
+     */
+    public int hashCode() {
+        return ((null == mHost) ? 0 : mHost.hashCode())
+        + ((null == mExclusionList) ? 0 : mExclusionList.hashCode())
+        + mPort;
+    }
+
     /**
      * Implement the Parcelable interface.
      * @hide