FITS: generating send-streams in portable format
This commit adds the command 'zfs fits-send', analogous to zfs send. The
generated send stream is compatible with the stream generated with that
from 'btrfs send' and can in principle easily be received to any filesystem.

*** 823,832 ****
--- 823,833 ----
          ZFS_IOC_SEND_PROGRESS,
          ZFS_IOC_LOG_HISTORY,
          ZFS_IOC_SEND_NEW,
          ZFS_IOC_SEND_SPACE,
          ZFS_IOC_CLONE,
+         ZFS_IOC_FITS_SEND,
          ZFS_IOC_LAST
  } zfs_ioc_t;
  
  /*
   * Internal SPA load state.  Used by FMA diagnosis engine.