Update validations on UNL change (RIPD-1566):

Change the trust status of existing validations based when nodes are
added or removed from the UNL.

src/ripple/overlay/impl/OverlayImpl.cpp

@@ -899,8 +899,12 @@ OverlayImpl::send (protocol::TMValidation& m)
     });
 
     SerialIter sit (m.validation().data(), m.validation().size());
-    auto val = std::make_shared <
-        STValidation> (std::ref (sit), false);
+    auto val = std::make_shared<STValidation>(
+        std::ref(sit),
+        [this](PublicKey const& pk) {
+            return calcNodeID(app_.validatorManifests().getMasterKey(pk));
+        },
+        false);
     app_.getOPs().pubValidation (val);
 }