tst_QDnsLookup: skip a unittest on Windows

See code review 496440 on Gerrit for the details.

Change-Id: Ibd32a44cf7e2e07f36687cc2f0eeaf3008f64e73
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

tests/auto/network/kernel/qdnslookup/tst_qdnslookup.cpp

@@ -225,6 +225,9 @@ void tst_QDnsLookup::lookupLocalhost()
 
 void tst_QDnsLookup::lookupRoot()
 {
+#ifdef Q_OS_WIN
+    QSKIP("This test fails on Windows as it seems to treat the lookup as a local one.");
+#else
     QDnsLookup lookup(QDnsLookup::Type::NS, u""_s);
     lookup.lookup();
     QTRY_VERIFY_WITH_TIMEOUT(lookup.isFinished(), Timeout);
@@ -236,6 +239,7 @@ void tst_QDnsLookup::lookupRoot()
         QCOMPARE(ns.name(), QString());
         QVERIFY(ns.value().endsWith(".root-servers.net"));
     }
+#endif
 }
 
 void tst_QDnsLookup::lookup_data()