cgroup: treat devices as "special" properties
cgroup: treat devices as "special" properties

v2: don't try to write "" to devices.allow, just skip it since we write 'a'
    to devices.deny everywhere anyway.
v3: leave cgroup prop name as "devices.list" so it is caught in the later
    tests for special-ness. also, don't write the last devices entry twice.

Signed-off-by: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>
CC: Cyrill Gorcunov <7a1ea01eee6961eb1e372e3508c2670446d086f4@openvz.org>
Acked-by: Cyrill Gorcunov <7a1ea01eee6961eb1e372e3508c2670446d086f4@openvz.org>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@virtuozzo.com>

eabatalov/criu,eabatalov/criu,eabatalov/criu,eabatalov/criu,eabatalov/criu,eabatalov/criu