3996 want a libzfs_core API to rollback to latest snapshot
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>

*** 263,273 ****
  int dsl_dataset_snap_lookup(dsl_dataset_t *ds, const char *name,
      uint64_t *value);
  int dsl_dataset_snap_remove(dsl_dataset_t *ds, const char *name, dmu_tx_t *tx);
  void dsl_dataset_set_refreservation_sync_impl(dsl_dataset_t *ds,
      zprop_source_t source, uint64_t value, dmu_tx_t *tx);
! int dsl_dataset_rollback(const char *fsname, void *owner);
  
  #ifdef ZFS_DEBUG
  #define dprintf_ds(ds, fmt, ...) do { \
          if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
          char *__ds_name = kmem_alloc(MAXNAMELEN, KM_SLEEP); \
--- 263,273 ----
  int dsl_dataset_snap_lookup(dsl_dataset_t *ds, const char *name,
      uint64_t *value);
  int dsl_dataset_snap_remove(dsl_dataset_t *ds, const char *name, dmu_tx_t *tx);
  void dsl_dataset_set_refreservation_sync_impl(dsl_dataset_t *ds,
      zprop_source_t source, uint64_t value, dmu_tx_t *tx);
! int dsl_dataset_rollback(const char *fsname, void *owner, nvlist_t *result);
  
  #ifdef ZFS_DEBUG
  #define dprintf_ds(ds, fmt, ...) do { \
          if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
          char *__ds_name = kmem_alloc(MAXNAMELEN, KM_SLEEP); \