ceph: use new D_COMPLETE dentry flag

We used to use a flag on the directory inode to track whether the dcache
contents for a directory were a complete cached copy.  Switch to a dentry
flag CEPH_D_COMPLETE that is safely updated by ->d_prune().

Signed-off-by: Sage Weil <sage@newdream.net>

diff --cc fs/ceph/caps.c
Simple merge

diff --cc fs/ceph/dir.c
Simple merge

diff --cc fs/ceph/inode.c
Simple merge

diff --cc fs/ceph/mds_client.c
Simple merge

diff --cc fs/ceph/super.h
Simple merge