vzctl set --mount_opts: fix a segfault

This (pretty stupid) bug was introduced in commit 287d0dc,
and led to segfault when initially setting mount options
for a running container.

http://bugzilla.openvz.org/2385

Reported-by: Dmitry Kopytov <kopytov@kopytov.ru>
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed