Skip tst_QGuiApplication::focusObject() on Mac OS X

This test fails intermittently, and at random locations.

Task-number: QTBUG-24322
Change-Id: Ied6dd4d1593066debc0fb48c6ca2a17a1f4d51b7
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>

tests/auto/gui/kernel/qguiapplication/tst_qguiapplication.cpp

@@ -78,6 +78,9 @@ public:
 
 void tst_QGuiApplication::focusObject()
 {
+#ifdef Q_OS_MAC
+    QSKIP("This test fails intermittently, and at different locations. See QTBUG-24322");
+#endif
     int argc = 0;
     QGuiApplication app(argc, 0);