Don't show evaluation popup for unsupported evaluation

Do not show the popup for unsupported evaluations on every launch of a
QWidget based application. This is causing problems e.g. for applications
that are run by Qt Creator in the background, like qmlpuppet.

Instead, we'll show a similar dialog on Qt Creator startup.

Change-Id: I6b44c24865ed6992a70f8a9dd0bcd08a4744cb28
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Sami Makkonen <sami.makkonen@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>

src/corelib/kernel/qtcore_eval.cpp

@@ -529,8 +529,6 @@ void qt_gui_eval_init(QCoreApplicationPrivate::Type type)
         box.exec();
         ::exit(0);
     } else {
-        EvalMessageBox *box = new EvalMessageBox(false);
-        box->show();
         Q_UNUSED(new QGuiFuriCuri());
     }
 }