Removed obsolete XInput mapping hint

include/SDL3/SDL_hints.h

@@ -2426,15 +2426,6 @@ extern "C" {
   */
 #define SDL_HINT_DIRECTINPUT_ENABLED "SDL_DIRECTINPUT_ENABLED"
 
-/**
- *  A variable that causes SDL to use the old axis and button mapping for XInput devices.
- *
- *  This hint is for backwards compatibility only and will be removed in SDL 2.1
- *
- *  The default value is "0".  This hint must be set before SDL_Init()
- */
-#define SDL_HINT_XINPUT_USE_OLD_JOYSTICK_MAPPING "SDL_XINPUT_USE_OLD_JOYSTICK_MAPPING"
-
 /**
  *  A variable that causes SDL to not ignore audio "monitors"
  *