Fix memory leak when opening and closing remux window without remuxing

The remuxer thread was only started if there was an actual remux job,
which resulted in the remuxer thread not being able to call the worker's
destructor (because it wasn't running)

obs/window-remux.cpp

@@ -58,6 +58,7 @@ OBSRemux::OBSRemux(const char *path, QWidget *parent)
 			this, &OBSRemux::inputChanged);
 
 	worker->moveToThread(&remuxer);
+	remuxer.start();
 
 	//gcc-4.8 can't use QPointer<RemuxWorker> below
 	RemuxWorker *worker_ = worker;
@@ -157,8 +158,6 @@ void OBSRemux::Remux()
 	ui->progressBar->setVisible(true);
 	ui->remux->setEnabled(false);
 
-	if (!remuxer.isRunning())
-		remuxer.start();
 	emit remux();
 }