sys/mount.h: sync with latest glibc

Newer glibc adds a few more MNT_* flags, so import them.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

include/sys/mount.h

@@ -96,8 +96,12 @@ enum
 /* Possible value for FLAGS parameter of `umount2'.  */
 enum
 {
-  MNT_FORCE = 1			/* Force unmounting.  */
+  MNT_FORCE = 1,		/* Force unmounting.  */
 #define MNT_FORCE MNT_FORCE
+  MNT_DETACH = 2,		/* Just detach from the tree.  */
+#define MNT_DETACH MNT_DETACH
+  MNT_EXPIRE = 4		/* Mark for expiry.  */
+#define MNT_EXPIRE MNT_EXPIRE
 };