Rebase and update stb_vorbis.h to SDL_sound's version :

- Keeps the original stb_vorbis as intact as possible so
  that future updates from mainstream would be painless.
- Reduces STB_VORBIS_MAX_CHANNELS from 16 to 6 (objections?)
- Adds several missing libm function overrides,
- SDL_mixer now requires SDL >= 2.0.9 because of SDL_exp()
- Fixes slow loads and leaks in start_decoder:
  nothings/stb#1174
- Fixes submap array out-of-bounds indexing bug:
  nothings/stb#1312
- Replace signed overflow clamps with unsigned overflow:
  nothings/stb#1168
- Replaces alloca() usage with setup_malloc() (from libxmp.)
- Fixes '-Wmaybe-uninitialized' warnings in get_seek_page_info:
  nothings/stb#1172
- A minor UBSan fix and suppression:
  nothings/stb#1168
- Fixes signature of dummy realloc() for STB_VORBIS_NO_CRT:
  nothings/stb#1198
- Renames BUFFER_SIZE macro to STB_BUFFER_SIZE:
  nothings/stb#1078
- Pulls in sample-accurate offset patch of Vitaly Novichkov:
  (stb_vorbis_get_playback_sample_offset, because it's used
  in OGG_Tell and OGG_GetSome):
  nothings/stb#1294
  nothings/stb#1295
- Fixes a few warnings here and there in some environments.
- Replaces two dummy '(void) 0' with 'do {} while(0)'

configure

@@ -15308,7 +15308,7 @@ find_lib()
     done
 }
 
-SDL_VERSION=2.0.7
+SDL_VERSION=2.0.9
 
 # Check whether --with-sdl-prefix was given.
 if test "${with_sdl_prefix+set}" = set; then :

configure.ac

@@ -251,7 +251,7 @@ find_lib()
 }
 
 dnl Check for SDL
-SDL_VERSION=2.0.7
+SDL_VERSION=2.0.9
 AM_PATH_SDL2($SDL_VERSION,
             :,
             AC_MSG_ERROR([*** SDL version $SDL_VERSION not found!])

src/codecs/music_ogg_stb.c

@@ -25,10 +25,46 @@
 
 #include "music_ogg.h"
 #include "utils.h"
+#include "SDL_assert.h"
+
+#define STB_VORBIS_SDL 1 /* for SDL_mixer-specific stuff. */
+#define STB_VORBIS_NO_STDIO 1
+#define STB_VORBIS_NO_CRT 1
+#define STB_VORBIS_NO_PUSHDATA_API 1
+#define STB_VORBIS_MAX_CHANNELS 6
+#define STBV_CDECL
+#define STB_FORCEINLINE SDL_FORCE_INLINE
+#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+#define STB_VORBIS_BIG_ENDIAN 1
+#endif
+
+#ifdef assert
+#undef assert
+#endif
+#ifdef memset
+#undef memset
+#endif
+#ifdef memcpy
+#undef memcpy
+#endif
+#define assert SDL_assert
+#define memset SDL_memset
+#define memcmp SDL_memcmp
+#define memcpy SDL_memcpy
+#define qsort SDL_qsort
+#define malloc SDL_malloc
+#define realloc SDL_realloc
+#define free SDL_free
+
+#define pow SDL_pow
+#define floor SDL_floor
+#define ldexp(v, e) SDL_scalbn((v), (e))
+#define abs(x) SDL_abs(x)
+#define cos(x) SDL_cos(x)
+#define sin(x) SDL_sin(x)
+#define log(x) SDL_log(x)
+#define exp(x) SDL_exp(x)
 
-#define OV_EXCLUDE_STATIC_CALLBACKS
-#define STB_VORBIS_NO_STDIO
-#define STB_VORBIS_NO_CRT
 #include "stb_vorbis/stb_vorbis.h"
 
 typedef struct {