use sys/soundcard.h for OSS audio

Originally committed as revision 607 to svn://svn.ffmpeg.org/ffmpeg/trunk

libav/audio.c

@@ -21,7 +21,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <linux/soundcard.h>
+#include <sys/soundcard.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/ioctl.h>