nfscl: return delegations in the NFS VOP_RECLAIM()

After a vnode is recycled it can no longer be
acquired via vfs_hash_get() and, as such,
a delegation for the vnode cannot be recalled.

In the unlikely event that a delegation still
exists when the vnode is being recycled, return
the delegation since it will no longer be
recallable.

Until you have this patch in your NFSv4 client,
you should consider avoiding the use of delegations.

MFC after: 2 weeks