[sdlsound] SDL_sound + MIDI on MacOS X.

[Ryan C. Gordon]

> SDL_mixer didn't have this particular bug, but seems to have other
> byteswapping bugs that prevent it from loading a MIDI file in the first
> place. If someone wants to diff the two codebases (SDL_sound's MIDI
> decoder is based on SDL_mixer's from way back) and figure out why, I'll
> get the SDL_mixer patch into CVS.

Call off the search, I already found the SDL_mixer bug (it's MacOS X
specific and not bigendian specific). Patched in CVS.

--ryan.