music_ogg: provide audio using the host endianness

This fixes two issues in big-endian devices:
- When using Tremor, Tremor doesn't swap the byte order, so it "respects" the
  endianness of the host. This change makes sure SDL_mixer creates a stream in
  AUDIO_S16SYS format (meaning S16 with the host endianness).
- Make also vorbis respect the host endianness. Before this change, ov_read was
  forced to always deliver data in little-endian order. That wouldn't work with
  the AUDIO_S16SYS change described above. Also, it means SDL would swap the
  bytes of ogg data twice in big-endian devices: first in ov_read to little-
  endian when reading ogg file, and then again in SDL_Convert_Byteswap before
  sending the data to the audio device.

The result of this is fixing Tremor support on big-endian devices and improving
performance/efficiency of Vorbis on big-endian devices.

Author: sergiou87

src/codecs/music_ogg.c

@@ -215,7 +215,7 @@ static int OGG_UpdateSection(OGG_music *music)
         music->stream = NULL;
     }
 
-    music->stream = SDL_NewAudioStream(AUDIO_S16, (Uint8)vi->channels, (int)vi->rate,
+    music->stream = SDL_NewAudioStream(AUDIO_S16SYS, (Uint8)vi->channels, (int)vi->rate,
                                        music_spec.format, music_spec.channels, music_spec.freq);
     if (!music->stream) {
         return -1;
@@ -421,7 +421,7 @@ static int OGG_GetSome(void *context, void *data, int bytes, SDL_bool *done)
 #ifdef OGG_USE_TREMOR
     amount = (int)vorbis.ov_read(&music->vf, music->buffer, music->buffer_size, &section);
 #else
-    amount = (int)vorbis.ov_read(&music->vf, music->buffer, music->buffer_size, 0, 2, 1, &section);
+    amount = (int)vorbis.ov_read(&music->vf, music->buffer, music->buffer_size, SDL_BYTEORDER == SDL_BIG_ENDIAN, 2, 1, &section);
 #endif
     if (amount < 0) {
         set_ov_error("ov_read", amount);