Be consistent about how we read and update the UI state variable

Core/System.cpp

@@ -72,7 +72,7 @@ enum CPUThreadState {
 
 MetaFileSystem pspFileSystem;
 ParamSFOData g_paramSFO;
-GlobalUIState globalUIState;
+static GlobalUIState globalUIState;
 static CoreParameter coreParameter;
 static PSPMixer *mixer;
 static std::thread *cpuThread = NULL;
@@ -96,6 +96,10 @@ void UpdateUIState(GlobalUIState newState) {
 	}
 }
 
+GlobalUIState GetUIState() {
+	return globalUIState;
+}
+
 bool IsAudioInitialised() {
 	return mixer != NULL;
 }