Patch to fix mgt_sandbox_unix if there're more than 10 groups

[Poul-Henning Kamp]

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In message <D1FB9E70-27C6-48AB-92D8-A4A938748C72 at gmail.com>, Meng Zhang writes:

>Please review and commit the patch to fix mgt_sandbox_unix.

I just bumbped NGID to 2000 instead. :-)

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Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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