cgroup: Use xmalloc in rewrite_cgsets
cgroup: Use xmalloc in rewrite_cgsets

We prefer x* helpers because they print error
in case of allocation failures.

Signed-off-by: Cyrill Gorcunov <7a1ea01eee6961eb1e372e3508c2670446d086f4@openvz.org>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

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