Core: Correct shutdown on late init failure.

Otherwise we leak and can't start again.  This happened when shutdown
completed quickly after thread start.

Core/System.cpp

@@ -447,7 +447,9 @@ bool PSP_InitStart(const CoreParameter &coreParam, std::string *error_string) {
 	bool success = !g_CoreParameter.fileToStart.empty();
 	if (!success) {
 		Core_NotifyLifecycle(CoreLifecycle::START_COMPLETE);
-		pspIsIniting = false;
+		// In this case, we must call shutdown since the caller won't know to.
+		// It must've partially started since CPU_Init returned true.
+		PSP_Shutdown();
 	}
 	return success;
 }