System: Allow GPU to have delayed loading.

Core/System.cpp

@@ -436,16 +436,16 @@ bool PSP_InitUpdate(std::string *error_string) {
 
 	bool success = coreParameter.fileToStart != "";
 	*error_string = coreParameter.errorString;
-	if (success) {
+	if (success && gpu == nullptr) {
 		success = GPU_Init(coreParameter.graphicsContext, coreParameter.thin3d);
 		if (!success) {
 			PSP_Shutdown();
 			*error_string = "Unable to initialize rendering engine.";
 		}
 	}
-	pspIsInited = success;
-	pspIsIniting = false;
-	return true;
+	pspIsInited = success && GPU_IsReady();
+	pspIsIniting = success && !pspIsInited;
+	return !success || pspIsInited;
 }
 
 bool PSP_Init(const CoreParameter &coreParam, std::string *error_string) {

GPU/GPU.cpp

@@ -55,6 +55,12 @@ static void SetGPU(T *obj) {
 #undef new
 #endif
 
+bool GPU_IsReady() {
+	if (gpu)
+		return gpu->IsReady();
+	return false;
+}
+
 bool GPU_Init(GraphicsContext *ctx, Draw::DrawContext *draw) {
 #if PPSSPP_PLATFORM(UWP)
 	SetGPU(new GPU_D3D11(ctx, draw));

GPU/GPU.h

@@ -105,4 +105,5 @@ namespace Draw {
 }
 
 bool GPU_Init(GraphicsContext *ctx, Draw::DrawContext *thin3d);
+bool GPU_IsReady();
 void GPU_Shutdown();

GPU/GPUCommon.h

@@ -70,6 +70,9 @@ public:
 	Draw::DrawContext *GetDrawContext() override {
 		return draw_;
 	}
+	bool IsReady() override {
+		return true;
+	}
 	void Reinitialize() override;
 
 	void BeginHostFrame() override;

GPU/GPUInterface.h

@@ -168,6 +168,7 @@ public:
 	virtual Draw::DrawContext *GetDrawContext() = 0;
 
 	// Initialization
+	virtual bool IsReady() = 0;
 	virtual void InitClear() = 0;
 	virtual void Reinitialize() = 0;