The MIDI synthesizer bundled with SDL_Mixer doesn't sound as good as
Windows' built-in software synthesizer.
This adds Windows native implementation of MAKO as win/mako.cpp. It
plays MIDI by writing out SMF to a temporary file and play it with MCI.
CD emulation (--playlist) is also implemented using MCI.
The PCM implementation is copyed from TOTO's original Win32 impl.
This removes SDL_mixer dependency in Windows.
Fixes#1.