ControllerEmu: Make BackgroundInput a global setting through the virtualization

This will allow us to simplify the checks for background input and push
them further down into the architecture, into the ControllerEmu layer.

The new setting isn't actually used yet, though.

Source/Core/InputCommon/ControllerEmu.h

@@ -14,6 +14,7 @@
 #include <vector>
 
 #include "Common/IniFile.h"
+#include "Core/ConfigManager.h"
 #include "InputCommon/GCPadStatus.h"
 #include "InputCommon/ControllerInterface/ControllerInterface.h"
 
@@ -114,6 +115,25 @@ public:
 			}
 		};
 
+		class BackgroundInputSetting : public Setting
+		{
+		public:
+			BackgroundInputSetting(const std::string &_name) : Setting(_name, false)
+			{
+				is_virtual = true;
+			}
+
+			void SetValue(ControlState new_value) override
+			{
+				SConfig::GetInstance().m_BackgroundInput = new_value;
+			}
+
+			ControlState GetValue() override
+			{
+				return SConfig::GetInstance().m_BackgroundInput;
+			}
+		};
+
 		ControlGroup(const std::string& _name, const unsigned int _type = GROUP_TYPE_OTHER) : name(_name), type(_type) {}
 		virtual ~ControlGroup() {}