Add missing header file sys/stat.h

This file defines the initial permission flags used by open when we
create a file using O_CREAT flag.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
diff --git a/yavta.c b/yavta.c
index 3a98804..d081ad8 100644
--- a/yavta.c
+++ b/yavta.c
@@ -31,6 +31,7 @@
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/select.h>
+#include <sys/stat.h>
 #include <sys/time.h>
 
 #include <linux/videodev2.h>