- make OSS backend optional

diff --git a/configure.in b/configure.in
index e872756..8d3ae94 100644
--- a/configure.in
+++ b/configure.in
@@ -69,6 +69,22 @@ if test "x$usejack" = "xyes"; then
 	CFLAGS="$CFLAGS -DJACK"
 fi

+useoss=yes
+
+AC_ARG_ENABLE(
+  oss,
+  AC_HELP_STRING([--enable-oss], [use OSS @<:@default=yes@:>@]),
+  [
+    if test "x$enableval" = "xno"; then
+      useoss=no
+    fi
+  ])
+
+AM_CONDITIONAL(HAVE_OSS, test "x$useoss" = "xyes")
+
+if test "x$useoss" = "xyes"; then
+	CFLAGS="$CFLAGS -DOSS"
+fi

 PKG_CHECK_MODULES([GLADE], [libglade-2.0])
 AC_SUBST(GLADE_CFLAGS)
diff --git a/src/lingot-audio-oss.c b/src/lingot-audio-oss.c
index ee43ae6..1e1b998 100644
--- a/src/lingot-audio-oss.c
+++ b/src/lingot-audio-oss.c
@@ -20,11 +20,13 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */

+#ifdef OSS
 #include <sys/soundcard.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/errno.h>
+#endif
 #include <fcntl.h>
 #include <unistd.h>
 #include <string.h>
@@ -38,6 +40,9 @@

 LingotAudioHandler* lingot_audio_oss_new(char* device, int sample_rate) {

+	LingotAudioHandler* audio = NULL;
+
+#ifdef OSS
 	int channels = 1;
 	int format = SAMPLE_FORMAT;
 	char error_message[100];
@@ -107,17 +112,25 @@ LingotAudioHandler* lingot_audio_oss_new(char* device, int sample_rate) {
 		lingot_msg_add_error(exception);
 	}

+#	else
+	lingot_msg_add_error(
+			_("The application has not been built with OSS support"));
+#	endif
+
 	return audio;
 }

 void lingot_audio_oss_destroy(LingotAudioHandler* audio) {
+#ifdef OSS
 	if (audio != NULL) {
 		close(audio->dsp);
 		free(audio->read_buffer);
 	}
+#endif
 }

 int lingot_audio_oss_read(LingotAudioHandler* audio) {
+#ifdef OSS
 	int i;
 	int read_size;

@@ -140,6 +153,8 @@ int lingot_audio_oss_read(LingotAudioHandler* audio) {
 		audio->flt_read_buffer[i] = audio->read_buffer[i];
 	}

+#endif
+
 	return 0;
 }

diff --git a/src/lingot-core.c b/src/lingot-core.c
index 0d5c31f..d5883c4 100644
--- a/src/lingot-core.c
+++ b/src/lingot-core.c
@@ -22,7 +22,9 @@

 #include <stdio.h>
 #include <math.h>
+#ifdef OSS
 #include <sys/soundcard.h>
+#endif
 #include <string.h>
 #include <errno.h>
 #include <sys/time.h>