Cannot use autoconf: http://sourceforge.net/p/opalvoip/feature-requests/18/

Index: plugins/configure
--- plugins/configure.orig
+++ plugins/configure
@@ -632,6 +632,7 @@ HAS_V4L
 HAS_AUDIOSHM
 HAS_SUNAUDIO
 HAS_PULSE
+HAS_SNDIO
 HAS_OSS
 HAS_ESD
 HAS_ALSA
@@ -709,6 +710,7 @@ enable_audio
 enable_alsa
 enable_esd
 enable_oss
+enable_sndio
 enable_pulse
 enable_sunaudio
 enable_shmaudio
@@ -1359,6 +1361,7 @@ disable plugin support]
   --enable-alsa           enable ALSA audio support
   --enable-esd            enable ESD audio support
   --enable-oss            enable OSS audio support
+  --enable-sndio       enable SNDIO audio support  
   --enable-pulse       enable Pulse audio support
   --enable-sunaudio            enable  Sun audio support
   --enable-shmaudio       enable shm audio support
@@ -3908,7 +3911,25 @@ $as_echo "no" >&6; }
   fi
 fi
 
+# Check whether --enable-sndio was given.
+if test "${enable_sndio+set}" = set; then :
+  enableval=$enable_sndio;
+else
+  enable_sndio=no
+fi
 
+PTLIB_SNDIO=no
+if test "x${enable_sndio}" = "xno" ; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: SNDIO audio disabled by user" >&5
+$as_echo "$as_me: SNDIO audio disabled by user" >&6;}
+else
+  ac_fn_c_check_header_mongrel "$LINENO" "sndio.h" "ac_cv_header_sndio_h" "$ac_includes_default"
+if test "x$ac_cv_header_sndio_h" = xyes; then :
+      HAS_SNDIO=1
+      PTLIB_SNDIO=yes
+fi
+fi
+
 # Check whether --enable-pulse was given.
 if test "${enable_pulse+set}" = set; then :
   enableval=$enable_pulse;
@@ -4048,7 +4069,7 @@ fi
 if test "${enable_v4l2}z" = "yesz" ; then
   case "$target_os" in
     solaris* | sunos* ) V4L2_HEADER="sys/videodev2.h"   ; ;;
-    netbsd* )           V4L2_HEADER="sys/videoio.h"     ; ;;
+    netbsd* | OpenBSD* ) V4L2_HEADER="sys/videoio.h"     ; ;;
           * )	        V4L2_HEADER="linux/videodev2.h" ; ;;
   esac
 
