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/dynapi/SDL_dynapi.c

@@ -19,11 +19,15 @@
   3. This notice may not be removed or altered from any source distribution.
 */
 
-#include "SDL_config.h"
+#include "build_config/SDL_build_config.h"
 #include "SDL_dynapi.h"
 
 #if SDL_DYNAMIC_API
 
+#ifdef HAVE_STDIO_H
+#include <stdio.h>
+#endif
+
 #include "SDL.h"
 
 /* These headers have system specific definitions, so aren't included above */

src/dynapi/SDL_dynapi_overrides.h

@@ -892,3 +892,4 @@
 #define SDL_EGL_SetEGLAttributeCallbacks SDL_EGL_SetEGLAttributeCallbacks_REAL
 #define SDL_GDKSuspendComplete SDL_GDKSuspendComplete_REAL
 #define SDL_GetWindowWMInfo SDL_GetWindowWMInfo_REAL
+#define SDL_memset4 SDL_memset4_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -968,3 +968,4 @@ SDL_DYNAPI_PROC(void,SDL_EGL_SetEGLAttributeCallbacks,(SDL_EGLAttribArrayCallbac
 SDL_DYNAPI_PROC(void,SDL_GDKSuspendComplete,(void),(),return)
 #endif
 SDL_DYNAPI_PROC(int,SDL_GetWindowWMInfo,(SDL_Window *a, SDL_SysWMinfo *b, Uint32 c),(a,b,c),return)
+SDL_DYNAPI_PROC(void*,SDL_memset4,(void *a, Uint32 b, size_t c),(a,b,c),return)