Default SDL_HINT_JOYSTICK_GAMEINPUT to SDL_FALSE

This was causing crashes in IGameInput_RegisterSystemButtonCallback(), presumably on older systems with runtimes using a different function signature. We'll just disable it for now until the GameInput runtime has stabilized and we can tell when it's safe to use.

include/SDL3/SDL_hints.h

@@ -1232,8 +1232,8 @@ extern "C" {
  *
  * The variable can be set to the following values:
  *
- * - "0": GameInput is not used.
- * - "1": GameInput is used. (default)
+ * - "0": GameInput is not used. (default)
+ * - "1": GameInput is used.
  *
  * This hint should be set before SDL is initialized.
  *