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.

*** 589,598 ****
--- 589,600 ----
  
  typedef boolean_t (snapfilter_cb_t)(zfs_handle_t *, void *);
  
  extern int zfs_send(zfs_handle_t *, const char *, const char *,
      sendflags_t *, int, snapfilter_cb_t, void *, nvlist_t **);
+ extern int zfs_fits_send(zfs_handle_t *, const char *, const char *,
+     sendflags_t *, int, snapfilter_cb_t, void *);
  
  extern int zfs_promote(zfs_handle_t *);
  extern int zfs_hold(zfs_handle_t *, const char *, const char *, boolean_t,
      boolean_t, boolean_t, int, uint64_t, uint64_t);
  extern int zfs_release(zfs_handle_t *, const char *, const char *, boolean_t);