fix '(qexec)' to work with QML Preview (Qt Designer) when used inside a fallback restart in Slime mode

src/ecl_fun.cpp

@@ -2741,7 +2741,6 @@ cl_object qexec2(cl_object l_milliseconds) {
         timer->start(toInt(l_milliseconds));
         EQL::eventLoop->exec();
         return l_milliseconds; }
-    QCoreApplication::exit(); // prevent "The event loop is already running"
     QApplication::exec();
     return ECL_T; }