Mark tst_QNetworkReply::getThenDeleteObject as unstable

It's unstable on all platforms, because the reply can be finished
due to a race with the http thread. It isn't crashing (which the
test was trying to test for), but rather the QVERIFY(!reply->isFinished())
fails, which is an inconclusive verdict.

Change-Id: Ib815a7cedd220544a0c9cb83023e3334df4a0fb3
Reviewed-by: Martin Petersson <Martin.Petersson@nokia.com>

tests/auto/network/access/qnetworkreply/tst_qnetworkreply.cpp

@@ -5632,6 +5632,7 @@ void tst_QNetworkReply::getAndThenDeleteObject_data()
 
 void tst_QNetworkReply::getAndThenDeleteObject()
 {
+    QSKIP("unstable test - reply may be finished too early");
     // yes, this will leak if the testcase fails. I don't care. It must not fail then :P
     QNetworkAccessManager *manager = new QNetworkAccessManager();
     QNetworkRequest request("http://" + QtNetworkSettings::serverName() + "/qtest/bigfile");