DolphinQt2: Add missing header guards for CheatCodeEditor and MappingIndicator

Prevents potential double inclusion issues from ever happening.

Source/Core/DolphinQt2/Config/CheatCodeEditor.h

@@ -2,6 +2,8 @@
 // Licensed under GPLv2+
 // Refer to the license.txt file included.
 
+#pragma once
+
 #include <QDialog>
 
 class QDialogButtonBox;

Source/Core/DolphinQt2/Config/Mapping/MappingIndicator.h

@@ -2,6 +2,8 @@
 // Licensed under GPLv2+
 // Refer to the license.txt file included.
 
+#pragma once
+
 #include <QWidget>
 
 namespace ControllerEmu