Currently if /tmp does not exist, CRIU fails because it will not be
able to create a temporary directory there.  But when checkpointing
and restoring containers, we cannot rely on the existence of /tmp.
For such containers, we should use root (/).  The temporary directory
will be removed after CRIU is done.
Signed-off-by: Saied Kazemi <saied@google.com>
Acked-by: Andrew Vagin <avagin@odin.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>