Remove SDL_config.h from the public headers

The SDL headers are no longer dependent on the build configuration.

Fixes https://github.com/libsdl-org/SDL/issues/6643 and https://github.com/libsdl-org/SDL/issues/6641

test/testjoystick.c

@@ -12,9 +12,7 @@
 
 /* Simple program to test the SDL joystick routines */
 
-#include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 
 #include "SDL.h"
 
@@ -22,8 +20,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#ifndef SDL_JOYSTICK_DISABLED
-
 #ifdef __IOS__
 #define SCREEN_WIDTH    320
 #define SCREEN_HEIGHT   480
@@ -326,15 +322,4 @@ main(int argc, char *argv[])
     return 0;
 }
 
-#else
-
-int
-main(int argc, char *argv[])
-{
-    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL compiled without Joystick support.\n");
-    return 1;
-}
-
-#endif
-
 /* vi: set ts=4 sw=4 expandtab: */