(run autoconf after this).  Note that the check has been altered to break
  out of the AC_CHECK_HEADERS after the first match - this is so
  <sys/soundcard.h>, if found on NetBSD (a `real' OSS), will not conflict
  with the emulated ossaudio.
- check for <soundcard.h> along with the other two in a mutually-exclusive
  manner in the various *.c files that need it; change include of
  "mmsystem.h" to "multimedia.h" so this logic is all in one place
- change mcicda.c to allow for CD audio manipulation on NetBSD.  This
  includes:
  * changing ioctl() calls to be NON-SPLIT with exactly 3 args; on NetBSD
    ossaudio, ioctl() is #defined to be _oss_ioctl by <soundcard.h>, and
    neither splitting with #-directives nor a two-arg ioctl work;
  * changing the #if logic to allow both FreeBSD and NetBSD to share the
    appropriate code blocks
- block out MIDI code for NetBSD (init.c) and/or missing SNDCTL_MIDI_INFO
  (midi.c, mcimidi.c).  NetBSD's OSS emulation does not (yet) support MIDI.
Thanks go to mycroft@netbsd.org for the 99% bulk of this work.