We plan to switch to Mounts-v2 engine for restoring mounts by default,
this options is to allow switching to old engine. This patch only adds
an option, no engine behind it yet.
Cherry-picked from Virtuozzo criu:
https://src.openvz.org/projects/OVZ/repos/criu/commits/503f9ad2c
Changes: allow --mntns-compat-mode option only on restore and only if
MOVE_MOUNT_SET_GROUP is supported (this also requires change in
unittest/mock.c), change id in rpc criu_opts.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
f2d1c7fab8