features_mask2str(): avoid extra delimiter

Avoid stuff like this:

 # vzlist -o ctid,features 500
      CTID FEATURES
       500 ,nfsd:on

and this:

 # grep FEATURES /etc/vz/conf/500.conf
 FEATURES=" nfsd:on"

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed