log: Open log file with O_APPEND
log: Open log file with O_APPEND

Otherwise multiple writers can screw each-other's messages.

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

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