btrfs-progs: qgroup assign: can't handle options

btrfs-progs: qgroup assign: can't handle options

"qgroup assign" is considered as working without any options
from the following commit.

commit 176aeca9a148 ("btrfs-progs: add getopt stubs where needed")

However, we can pass options to this command.

* actual result

   ==================================================
   # ./btrfs qgroup assign --rescan 0/260 1/261 /btrfs
   btrfs qgroup assign: unrecognized option '--rescan'
   usage: btrfs qgroup assign [options] <src> <dst> <path>

       Assign SRC as the child qgroup of DST

       --rescan       schedule qutoa rescan if needed
       --no-rescan

   ==================================================

* expected result

   ==================================================
   # ./btrfs qgroup assign --rescan 0/260 1/261 /btrfs
   #
   ==================================================

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>