cstyle fixes
dsl_dataset_set_fsid_guid should use ZFS_SPACE_CHECK_RESERVED
dsl_dataset_set_fsid_guid _check and _sync func declared static,
removed from dsl_dataset.h
rewrite unique_valid
6333 ZFS should let the user specify or modify the fsid_guid of a dataset

*** 147,156 ****
--- 147,157 ----
          ZFS_PROP_FILESYSTEM_COUNT,
          ZFS_PROP_SNAPSHOT_COUNT,
          ZFS_PROP_REDUNDANT_METADATA,
          ZFS_PROP_PREV_SNAP,
          ZFS_PROP_RECEIVE_RESUME_TOKEN,
+         ZFS_PROP_FSID_GUID,
          ZFS_NUM_PROPS
  } zfs_prop_t;
  
  typedef enum {
          ZFS_PROP_USERUSED,