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

@@ -2402,10 +2402,13 @@
                 return (-1);
 
         VERIFY(0 == nvpair_value_uint64(pair, &intval));
 
         switch (prop) {
+        case ZFS_PROP_FSID_GUID:
+                err = dsl_dataset_set_fsid_guid(dsname, source, intval);
+                break;
         case ZFS_PROP_QUOTA:
                 err = dsl_dir_set_quota(dsname, source, intval);
                 break;
         case ZFS_PROP_REFQUOTA:
                 err = dsl_dataset_set_refquota(dsname, source, intval);