zdtm/mnt_tracefs: mount tracefs and don't affect an external mount namepace
zdtm/mnt_tracefs: mount tracefs and don't affect an external mount namepace

====================== Run zdtm/static/mnt_tracefs in uns ======================
Start test
./mnt_tracefs --pidfile=mnt_tracefs.pid --outfile=mnt_tracefs.out --dirname=mnt_tracefs.test
Run criu dump
Wait for zdtm/static/mnt_tracefs to die for 0.100000
Run criu restore
Run criu dump
Run criu restore
Run criu dump
Run criu restore
1: Old mounts lost: set([])
1: New mounts appeared: set([('/', '/debugfs/tracing')])
Wait for zdtm/static/mnt_tracefs to die for 0.100000

Cc: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>
Signed-off-by: Andrew Vagin <74c05afa918858348d6db8037d82fa8124870113@virtuozzo.com>
Acked-by: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@virtuozzo.com>

KKoukiou/criu-remote,KKoukiou/criu-remote,efiop/criu,eabatalov/criu,eabatalov/criu,eabatalov/criu,KKoukiou/criu-remote,KKoukiou/criu-remote,efiop/criu,eabatalov/criu,efiop/criu,efiop/criu,efiop/criu,KKoukiou/criu-remote,eabatalov/criu,efiop/criu,eabatalov/criu,KKoukiou/criu-remote