mount: skip the criu's mount namespace if tasks live in another mntns
mount: skip the criu's mount namespace if tasks live in another mntns

Currently here is a bug, because when we see criu's mount namespace,
we go to the "out" mark and don't validate mounts.

Reported-by: Cyrill Gorcunov <7a1ea01eee6961eb1e372e3508c2670446d086f4@openvz.org>
Signed-off-by: Andrey Vagin <74c05afa918858348d6db8037d82fa8124870113@openvz.org>
Acked-by: Cyrill Gorcunov <7a1ea01eee6961eb1e372e3508c2670446d086f4@openvz.org>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

fbocharov/criu,sdgdsffdsfff/criu,eabatalov/criu,wtf42/criu,KKoukiou/criu-remote,gablg1/criu,efiop/criu,gonkulator/criu,rentzsch/criu,wtf42/criu,efiop/criu,marcosnils/criu,AuthenticEshkinKot/criu,AuthenticEshkinKot/criu,marcosnils/criu,gablg1/criu,biddyweb/criu,tych0/criu,biddyweb/criu,KKoukiou/criu-remote,eabatalov/criu,svloyso/criu,biddyweb/criu,ldu4/criu,wtf42/criu,marcosnils/criu,eabatalov/criu,KKoukiou/criu-remote,efiop/criu,KKoukiou/criu-remote,LK4D4/criu,eabatalov/criu,AuthenticEshkinKot/criu,KKoukiou/criu-remote,AuthenticEshkinKot/criu,biddyweb/criu,LK4D4/criu,marcosnils/criu,gonkulator/criu,KKoukiou/criu-remote,fbocharov/criu,svloyso/criu,rentzsch/criu,AuthenticEshkinKot/criu,wtf42/criu,rentzsch/criu,rentzsch/criu,fbocharov/criu,efiop/criu,svloyso/criu,gonkulator/criu,ldu4/criu,biddyweb/criu,sdgdsffdsfff/criu,gablg1/criu,biddyweb/criu,rentzsch/criu,fbocharov/criu,gonkulator/criu,efiop/criu,tych0/criu,gablg1/criu,sdgdsffdsfff/criu,sdgdsffdsfff/criu,eabatalov/criu,fbocharov/criu,LK4D4/criu,eabatalov/criu,marcosnils/criu,gablg1/criu,gonkulator/criu,AuthenticEshkinKot/criu,fbocharov/criu,rentzsch/criu,gonkulator/criu,sdgdsffdsfff/criu,ldu4/criu,LK4D4/criu,wtf42/criu,marcosnils/criu,wtf42/criu,tych0/criu,LK4D4/criu,tych0/criu,ldu4/criu,sdgdsffdsfff/criu,tych0/criu,efiop/criu,svloyso/criu,svloyso/criu,gablg1/criu,svloyso/criu,ldu4/criu,tych0/criu,ldu4/criu,LK4D4/criu