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

*** 45,54 ****
--- 45,60 ----
  uint64_t unique_create(void);
  
  /* Return a unique value, which equals the one passed in if possible. */
  uint64_t unique_insert(uint64_t value);
  
+ /*
+  * Return B_TRUE if the passed value does not exist and is valid,
+  * B_FALSE otherwise
+  */
+ boolean_t unique_valid(uint64_t value);
+ 
  /* Indicate that this value no longer needs to be uniquified against. */
  void unique_remove(uint64_t value);
  
  #ifdef  __cplusplus
  }