include sys/select.h instead of unistd.h to get select,

according to posix 2001, fix compilation on freebsd 5.5

Originally committed as revision 15405 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rtsp.c

@@ -26,7 +26,7 @@
 #include "avformat.h"
 
 #include <sys/time.h>
-#include <unistd.h> /* for select() prototype */
+#include <sys/select.h>
 #include <strings.h>
 #include "network.h"
 #include "rtsp.h"