Activate mediaview instead of main window.

If the mediaview is currently shown and we receive an activation
event for the main window we should activate and focus mediaview.

Telegram/SourceFiles/platform/linux/main_window_linux.cpp

@@ -567,9 +567,6 @@ void MainWindow::psFirstShow() {
 void MainWindow::psInitSysMenu() {
 }
 
-void MainWindow::psUpdateSysMenu(Qt::WindowState state) {
-}
-
 void MainWindow::psUpdateMargins() {
 }