Update SDL2 to version 2.28.1.

libs/SDL2/include/SDL_rwops.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -45,9 +45,6 @@ extern "C" {
 #define SDL_RWOPS_JNIFILE   3U  /**< Android asset */
 #define SDL_RWOPS_MEMORY    4U  /**< Memory stream */
 #define SDL_RWOPS_MEMORY_RO 5U  /**< Read-Only memory stream */
-#if defined(__VITA__)
-#define SDL_RWOPS_VITAFILE  6U  /**< Vita file */
-#endif
 
 /**
  * This is the read/write operation structure -- very basic.
@@ -101,7 +98,7 @@ typedef struct SDL_RWops
         {
             void *asset;
         } androidio;
-#elif defined(__WIN32__)
+#elif defined(__WIN32__) || defined(__GDK__)
         struct
         {
             SDL_bool append;
@@ -113,17 +110,6 @@ typedef struct SDL_RWops
                 size_t left;
             } buffer;
         } windowsio;
-#elif defined(__VITA__)
-        struct
-        {
-            int h;
-            struct
-            {
-                void *data;
-                size_t size;
-                size_t left;
-            } buffer;
-        } vitaio;
 #endif
 
 #ifdef HAVE_STDIO_H