Add test construct for RtNetlinkLinkMessage

Test: TH
Change-Id: I00b8bd394e0666ecd79dc55fb1e53fecd7c94837
diff --git a/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java b/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java
index df7010e..0c49edc 100644
--- a/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java
+++ b/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java
@@ -62,6 +62,17 @@
         mInterfaceName = null;
     }
 
+    @VisibleForTesting
+    public RtNetlinkLinkMessage(@NonNull StructNlMsgHdr nlmsghdr,
+            int mtu, @NonNull StructIfinfoMsg ifinfomsg, @NonNull MacAddress hardwareAddress,
+            @NonNull String interfaceName) {
+        super(nlmsghdr);
+        mMtu = mtu;
+        mIfinfomsg = ifinfomsg;
+        mHardwareAddress = hardwareAddress;
+        mInterfaceName = interfaceName;
+    }
+
     public int getMtu() {
         return mMtu;
     }