Update SDL2 to newest version to fix 7.1 playback

This fixes 7.1 playback. Before this commit, SDL used 7.1 front audio configuration with Center Left and Center Right speakers, but without Rear speakers.

See https://github.com/libsdl-org/SDL/issues/11709 for more details.

libs/SDL2/include/SDL_config_winrt.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2024 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
@@ -54,7 +54,7 @@
 
 /* Useful headers */
 #define HAVE_DXGI_H 1
-#if WINAPI_FAMILY != WINAPI_FAMILY_PHONE_APP
+#if !SDL_WINAPI_FAMILY_PHONE
 #define HAVE_XINPUT_H 1
 #endif
 
@@ -161,7 +161,7 @@
 #define SDL_AUDIO_DRIVER_DUMMY  1
 
 /* Enable various input drivers */
-#if WINAPI_FAMILY == WINAPI_FAMILY_PHONE_APP
+#if SDL_WINAPI_FAMILY_PHONE
 #define SDL_JOYSTICK_DISABLED 1
 #define SDL_HAPTIC_DISABLED 1
 #else
@@ -208,9 +208,9 @@
 #define SDL_VIDEO_RENDER_D3D11  1
 
 /* Disable D3D12 as it's not implemented for WinRT */
-#define SDL_VIDEO_RENDER_D3D12  0
+/* #undef SDL_VIDEO_RENDER_D3D12 */
 
-#if SDL_VIDEO_OPENGL_ES2
+#ifdef SDL_VIDEO_OPENGL_ES2
 #define SDL_VIDEO_RENDER_OGL_ES2 1
 #endif