Use first available CD drive on Windows as default.
Windows code style fixes.
Fixed missing variable declaration and use snprintf instead of sprintf_s.
Make default_device thread-local

Signed-off-by: Philipp Wolfer <ph.wolfer@gmail.com>
Use a local variable to store the temporary device names in mb_disc_get_default_device_unportable.
Merge branch 'win_use_first_audio_drive'

see pull request #20 (LIB-43)

I also removed some trailing spaces.