OSS: include both /dev/dsp and /dev/dsp0

OSS: include both /dev/dsp and /dev/dsp0

On FreeBSD /dev/dsp is the default device but may not be /dev/dsp0.
PortAudio in the FreeBSD ports collection initially had a patch to
replace the default device with /dev/dsp (for example, with three
devices and /dev/dsp1 as the default we'd have /dev/dsp0, /dev/dsp,
/dev/dsp2).  This caused some trouble (the first device is no longer
default) and was later replaced with this change, leaving /dev/dsp
as the first entry, and just adding each /dev/dsp%d that exists.

FreeBSD bugs 208968 and 236118.