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

*** 1482,1491 ****
--- 1482,1497 ----
                  } else {
                          (void) zfs_standard_error(hdl, err, errbuf);
                  }
                  break;
  
+         case EEXIST:
+                 zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+                     "fsid_guid is invalid or already in use"));
+                 (void) zfs_error(hdl, EZFS_BADPROP, errbuf);
+                 break;
+ 
          case EOVERFLOW:
                  /*
                   * This platform can't address a volume this big.
                   */
  #ifdef _ILP32
*** 2491,2500 ****
--- 2497,2507 ----
                          free(ascii);
                  }
                  break;
  
          case ZFS_PROP_GUID:
+         case ZFS_PROP_FSID_GUID:
                  /*
                   * GUIDs are stored as numbers, but they are identifiers.
                   * We don't want them to be pretty printed, because pretty
                   * printing mangles the ID into a truncated and useless value.
                   */
*** 3276,3285 ****
--- 3283,3297 ----
                  case ENOTSUP:
                          zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                              "pool must be upgraded to set this "
                              "property or value"));
                          return (zfs_error(hdl, EZFS_BADVERSION, errbuf));
+ 
+                 case EEXIST:
+                         zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+                             "fsid_guid is invalid or already in use"));
+                         return (zfs_error(hdl, EZFS_BADPROP, errbuf));
  #ifdef _ILP32
                  case EOVERFLOW:
                          /*
                           * This platform can't address a volume this big.
                           */