frontend: Use Q_OBJECT macro for BrowserDock

This is needed as the BrowserDock is a QObject.

frontend/docks/BrowserDock.cpp

@@ -1,6 +1,7 @@
 #include "BrowserDock.hpp"
 
 #include <QCloseEvent>
+#include "moc_BrowserDock.cpp"
 
 void BrowserDock::closeEvent(QCloseEvent *event)
 {

frontend/docks/BrowserDock.hpp

@@ -8,6 +8,8 @@ extern QCef *cef;
 extern QCefCookieManager *panel_cookies;
 
 class BrowserDock : public OBSDock {
+	Q_OBJECT
+
 private:
 	QString title;