* fhandler.h (class fhandler_dev_dsp): Add class Audio, class Audio_in
and class Audio_out members and audio_in_, audio_out_ pointers so
that future changes are restricted to file fhandler_dsp.cc.
* fhandler_dsp.cc (fhandler_dev_dsp::Audio): Add this class to treat
things common to audio recording and playback.
Add more format conversions.
(fhandler_dev_dsp::Audio::queue): New queues for buffer management
to fix incomplete cleanup of buffers passed to the wave device.
(fhandler_dev_dsp::Audio_in): New, added class to implement audio
recording.
(fhandler_dev_dsp::Audio_out): Rework to use functionality provided
by fhandler_dev_dsp::Audio. Allocate memory audio buffers late,
just before write.
(fhandler_dev_dsp::Audio_out::start): Size of wave buffer allocated
here depends on audio rate/bits/channels.
(fhandler_dev_dsp::Audio_in::start): Ditto.
(fhandler_dev_dsp::setupwav): Replaced by following function.
(fhandler_dev_dsp::Audio_out::parsewav): Does not setup wave device
any more. Discard wave header properly.
(fhandler_dev_dsp::open): Add O_RDONLY and_RDWR as legal modes.
Protect against re-open. Activate fork_fixup.
(fhandler_dev_dsp::ioctl): Protect against actions when audio is
active. SNDCTL_DSP_GETFMTS only returns formats supported by
mmsystem wave API, not all supported formats. SNDCTL_DSP_GETBLKSIZE
result now depends on current audio format.
(fhandler_dev_dsp::fixup_after_fork): Call fork_fixup for the Audio
classes to let them duplicate the CRITICAL_SECTION.