Port away from deprecated QDateTime::toTime_t()

imports/activitymanager/sortedactivitiesmodel.cpp

@@ -310,7 +310,7 @@ QVariant SortedActivitiesModel::data(const QModelIndex &index, int role) const
             return QVariant(time);
 
         } else {
-            const auto now = QDateTime::currentDateTime().toTime_t();
+            const auto now = QDateTime::currentDateTime().toSecsSinceEpoch();
 
             if (time == 0)
                 return i18n("Used some time ago");

imports/activitymanager/switcherbackend.cpp

@@ -291,7 +291,7 @@ void SwitcherBackend::onCurrentActivityChanged(const QString &id)
     KConfig config(QStringLiteral("kactivitymanagerd-switcher"));
     KConfigGroup times(&config, "LastUsed");
 
-    const auto now = QDateTime::currentDateTime().toTime_t();
+    const auto now = QDateTime::currentDateTime().toSecsSinceEpoch();
 
     // Updating the time for the activity we just switched to
     // in the case we do not power off properly, and on the next