Stabilize tst_QAccessibility::actionTest

show() on a window is asynchronous.  Wait for it to complete before
continuing with the test.

Change-Id: Icd0daa0c0e8f287171c57708bb2fce0b6cf0906a
Reviewed-by: Toby Tomkins <toby.tomkins@nokia.com>
Reviewed-by: Kalle Lehtonen <kalle.ju.lehtonen@nokia.com>

tests/auto/other/qaccessibility/tst_qaccessibility.cpp

@@ -777,6 +777,7 @@ void tst_QAccessibility::actionTest()
     {
     QPushButton *button = new QPushButton;
     button->show();
+    QTest::qWaitForWindowShown(button);
     button->clearFocus();
     QCOMPARE(button->hasFocus(), false);
     QAccessibleInterface *interface = QAccessible::queryAccessibleInterface(button);