zfs-send(8): Restore sorting of flags

Before #11710 the flags in zfs-send(8) were sorted.
Restore order and bump the date.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #11905