SDL-based audio.

code/unix/linux_snd.c

@@ -19,6 +19,9 @@ along with Foobar; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 ===========================================================================
 */
+
+#if !USE_SDL
+
 #include <unistd.h>
 #include <fcntl.h>
 #include <stdlib.h>
@@ -291,3 +294,6 @@ void SNDDMA_Submit(void)
 void SNDDMA_BeginPainting (void)
 {
 }
+
+#endif // !USE_SDL
+