Util: Allow setting instance pointer manually, ex: in constructor

src/ruc/singleton.h

@@ -29,7 +29,9 @@ public:
 
 	static inline void destroy()
 	{
-		VERIFY(s_instance, "singleton does not exist");
+		if (!s_instance) {
+			return;
+		}
 
 		delete s_instance;
 		s_instance = nullptr;
@@ -44,6 +46,13 @@ public:
 protected:
 	Singleton() {}
 
+	// Hack: in certain situations the instance needs to be set early
+	static void set(T* instance)
+	{
+		VERIFY(!s_instance, "singleton already exists");
+		s_instance = instance;
+	}
+
 	// Constructor token
 	struct s {};