s4:ntvfs: Fix string copy of share_name

s4:ntvfs: Fix string copy of share_name

../source4/ntvfs/ipc/rap_server.c:70:3: error: ‘strncpy’ specified bound 13 equals destination size [-Werror=stringop-truncation]
   strncpy((char *)r->out.info[j].info1.share_name,
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    snames[i],
    ~~~~~~~~~~
    sizeof(r->out.info[0].info1.share_name));
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>
(cherry picked from commit 609ef35c12900bbd5ecaa557f7b5d71b5784a103)