add linux/fs for MS_MOVE support

Change-Id: If025d878f7e001135fd0ddf704dab3a6ffa77e2a
diff --git a/mount.c b/mount.c
index 6c52cc1..f2070a5 100644
--- a/mount.c
+++ b/mount.c
@@ -12,6 +12,7 @@
 #include <unistd.h>
 
 #include <linux/loop.h>
+#include <linux/fs.h>
 
 #define ARRAY_SIZE(x)	(sizeof(x) / sizeof(x[0]))