unix: Check service client for being null
unix: Check service client for being null

For regular dumps this thing is not initialized.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

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