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/testautomation_platform.c

@@ -2,9 +2,6 @@
  * Original code: automated SDL platform test written by Edgar Simo "bobbens"
  * Extended and updated by aschiffler at ferzkopp dot net
  */
-
-#include <stdio.h>
-
 #include "SDL.h"
 #include "SDL_test.h"
 
@@ -604,3 +601,5 @@ SDLTest_TestSuiteReference platformTestSuite = {
     platformTests,
     NULL
 };
+
+/* vi: set ts=4 sw=4 expandtab: */