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

src/sensor/dummy/SDL_dummysensor.c

@@ -20,8 +20,6 @@
 */
 #include "../../SDL_internal.h"
 
-#include "SDL_config.h"
-
 #if defined(SDL_SENSOR_DUMMY) || defined(SDL_SENSOR_DISABLED)
 
 #include "SDL_error.h"

src/sensor/dummy/SDL_dummysensor.h

@@ -18,6 +18,6 @@
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
-#include "SDL_config.h"
+#include "../../SDL_internal.h"
 
 /* vi: set ts=4 sw=4 expandtab: */