fsnotify: vfsmount marks generic functions

Much like inode-mark.c has all of the code dealing with marks on inodes
this patch adds a vfsmount-mark.c which has similar code but is intended
for marks on vfsmounts.

Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/fs/notify/Makefile b/fs/notify/Makefile
index 8f7f3b0..ae5f33a 100644
--- a/fs/notify/Makefile
+++ b/fs/notify/Makefile
@@ -1,5 +1,5 @@
 obj-$(CONFIG_FSNOTIFY)		+= fsnotify.o notification.o group.o inode_mark.o \
-				   mark.o
+				   mark.o vfsmount_mark.o
 
 obj-y			+= dnotify/
 obj-y			+= inotify/