r419598 tried to solve a problem where when hw.snd.default_unit is
set to anything except zero /dev/dsp0 is not available to programs
using portaudio since it assumes that /dev/dsp and /dev/dsp0 are
the same device.
However with that fix, when hw.snd.default_unit=1 and
hw.snd.basename_clone=0, portaudio will hide /dev/dsp1 from the
device list since it will use /dev/dsp for it instead of /dev/dsp1.
However since /dev/dsp is not available, QueryDevice() will fail
and /dev/dsp1 will never be added to the device list.
Instead of looking up hw.snd.default_unit we can solve this by
always trying to add /dev/dsp to the device list first.
PR: 236118
Submitted by: Tatsuki Makino <tatsuki_makino@hotmail.com>
0b56170026