avformat/unix: reshuffle #includes

This should fix openbsd while hopefully also working on solaris & android
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/unix.c

@@ -26,13 +26,11 @@
  *
  */
 
-#include <sys/socket.h>
-#include <sys/un.h>
-
 #include "libavutil/avstring.h"
 #include "libavutil/opt.h"
 #include "os_support.h"
 #include "network.h"
+#include <sys/un.h>
 #include "url.h"
 
 typedef struct UnixContext {