GDScript: Optimize operators by assuming the types

This assumes that operators are called usually with the same type of
operands as the first time. So it stores the types of the first run and
if matched it uses an optimized path by calling the validated operator
function directly. Otherwise it uses the regular untyped evaluator.

With this change, if operators do use the same type they run quite
faster. OTOH, if the types mismatch it takes longer to run than they
would with the previous code.

modules/gdscript/gdscript_function.h

@@ -473,7 +473,7 @@ private:
 	MethodBind **_methods_ptr = nullptr;
 	int _lambdas_count = 0;
 	GDScriptFunction **_lambdas_ptr = nullptr;
-	const int *_code_ptr = nullptr;
+	int *_code_ptr = nullptr;
 	int _code_size = 0;
 	int _argument_count = 0;
 	int _stack_size = 0;