dump: fix return code in message on pre-dump failure
dump: fix return code in message on pre-dump failure

Obviously we should print pre_dump_ret value if pre-dump failed.

Signed-off-by: Andrey Ryabinin <1db0f9e76dd8a9115570382660c6cd919b5a95b9@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

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