Add missing sys/select.h #include, fixes compilation on FreeBSD 7.0.

patch by Alexis Ballier, alexis.ballier gmail com

Originally committed as revision 15649 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavdevice/audio.c

@@ -34,6 +34,7 @@
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include <sys/time.h>
+#include <sys/select.h>
 
 #include "libavutil/log.h"
 #include "libavcodec/avcodec.h"