use qWaitForWindowExposed instead of qWaitForWindowActive

The qWaitForWindowActive() function returns false when the test is
run inside Xvfb and there is no window manager.
Forwarded: no
Last-Update: 2019-04-21

Gbp-Pq: Name wait_for_window_exposed.patch

tests/auto/quicktest/signalspy/tst_signalspy.cpp

@@ -73,7 +73,7 @@ void tst_SignalSpy::testCount()
     window.resize(200, 200);
     window.setSource(testFileUrl("signalspy.qml"));
     window.show();
-    QVERIFY(QTest::qWaitForWindowActive(&window));
+    QVERIFY(QTest::qWaitForWindowExposed(&window));
     QVERIFY(window.rootObject() != nullptr);
 
     QObject *mouseSpy = window.rootObject()->findChild<QObject*>("mouseSpy");