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/main/gdk/SDL_gdk_main.c

@@ -18,7 +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 this so we define UNICODE properly */
 #include "../../core/windows/SDL_windows.h"

src/main/ps2/SDL_ps2_main.c

@@ -2,7 +2,7 @@
     SDL_ps2_main.c, fjtrujy@gmail.com 
 */
 
-#include "SDL_config.h"
+#include "SDL_platform.h"
 
 #ifdef __PS2__
 
@@ -12,6 +12,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <stdio.h>
 
 #include <kernel.h>
 #include <sifrpc.h>

src/main/psp/SDL_psp_main.c

@@ -1,7 +1,7 @@
 /*
     SDL_psp_main.c, placed in the public domain by Sam Lantinga  3/13/14
 */
-#include "SDL_config.h"
+#include "SDL_platform.h"
 
 #ifdef __PSP__
 

src/main/windows/SDL_windows_main.c

@@ -3,7 +3,7 @@
 
     The WinMain function -- calls your program's main() function
 */
-#include "SDL_config.h"
+#include "SDL_platform.h"
 
 #ifdef __WIN32__