* t/alsa_improvements:
alsa: Remove pointless initialization.
alsa_mix: Allow non-positive mixer values.
alsa: New writer option: --buffer-time.
alsa: Work around poll fd problems.
alsa: Set period time.
alsa: Also dump hardware params.
alsa: Improve help text of --device.
alsa: Improve documentation of struct private_alsa_write_data.
alsa: Don't set t->error in ->pre_select().