* sound.c: Don't assume sizes fit in 'int'.

* sound.c: Don't assume sizes fit in 'int'.

(struct sound_device.period_size, alsa_period_size):
Return size_t, not int.
(struct sound_device.write, vox_write, alsa_write):
Accept size_t, not int.
(wav_play, au_play): Use size_t to store sizes, and ssize_t to
record read return values.