I've made a sweep package for NetBSD. Although, I've
encountered some problems that you may want to know.
The first one is that when you detect ossaudio, you do
not add it to linker flags. The patch I propose may not
be good (you will prefer AC_CHECK_LIB, I've just seen
it). The second problem is with the solaris audio. I
have an audioio.h header in NetBSD, but no stropts.h,
so it fails. The patch also fixes it. The other patch
adds a NULL argument when calling ioctl's (two
arguments won't work). I'm not sure if this is ok.