zdtm.py: skip the uns flavor if userns isn't suppported
zdtm.py: skip the uns flavor if userns isn't suppported

Signed-off-by: Andrew Vagin <74c05afa918858348d6db8037d82fa8124870113@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

AuthenticEshkinKot/criu,wtf42/criu,efiop/criu,eabatalov/criu,fbocharov/criu,fbocharov/criu,AuthenticEshkinKot/criu,KKoukiou/criu-remote,ldu4/criu,AuthenticEshkinKot/criu,eabatalov/criu,efiop/criu,ldu4/criu,ldu4/criu,eabatalov/criu,fbocharov/criu,tych0/criu,tych0/criu,tych0/criu,fbocharov/criu,ldu4/criu,tych0/criu,svloyso/criu,AuthenticEshkinKot/criu,KKoukiou/criu-remote,KKoukiou/criu-remote,eabatalov/criu,KKoukiou/criu-remote,wtf42/criu,AuthenticEshkinKot/criu,efiop/criu,KKoukiou/criu-remote,tych0/criu,ldu4/criu,efiop/criu,eabatalov/criu,fbocharov/criu,ldu4/criu,efiop/criu,eabatalov/criu,tych0/criu,svloyso/criu,svloyso/criu,wtf42/criu,wtf42/criu,wtf42/criu,svloyso/criu,wtf42/criu,fbocharov/criu,svloyso/criu,AuthenticEshkinKot/criu,KKoukiou/criu-remote,efiop/criu,svloyso/criu