Fix build with Qt 5.11.

Bug: https://bugs.gentoo.org/661596

--- a/App/CanvasAppliance.h
+++ b/App/CanvasAppliance.h
@@ -17,6 +17,9 @@
 
 #include "Shared/PlugGui/AbstractAppliance.h"
 #include "ui_CanvasAppliance.h"
+
+#include <QActionGroup>
+
 class QMenu;
 class AbstractContent;
 class Canvas;

--- a/3rdparty/likebackfrontend/LikeBackDialog.cpp
+++ b/3rdparty/likebackfrontend/LikeBackDialog.cpp
@@ -37,6 +37,7 @@
 #include "LikeBackDialog.h"
 
 #include <QApplication>
+#include <QButtonGroup>
 #include <QLocale>
 #include <QMessageBox>
 #include <QNetworkAccessManager>