joystick: SDL_VirtualJoystickDesc no longer takes a struct version.

If we need to extend this in the future, we'll make a second struct and
a second SDL_AttachVirtualJoystickEx-style function that uses it.

Just zero the struct and don't set a version.

Fixes #9489.

test/testcontroller.c

@@ -1117,7 +1117,6 @@ static void OpenVirtualGamepad(void)
     }
 
     SDL_zero(desc);
-    desc.version = SDL_VIRTUAL_JOYSTICK_DESC_VERSION;
     desc.type = SDL_JOYSTICK_TYPE_GAMEPAD;
     desc.naxes = SDL_GAMEPAD_AXIS_MAX;
     desc.nbuttons = SDL_GAMEPAD_BUTTON_MAX;