r17831: Attempt to fix the build farm: 0x7fffffffffffffff needs special casing too I

r17831: Attempt to fix the build farm: 0x7fffffffffffffff needs special casing too I
think. This broke 'make test' because the newly created user was set to be
kicked off Mi, 22 Jan 1975 23:55:33 CET (unix time 159663333) with the
setuserinfo21 call.

I'm not 100% sure that 0x7ff... means max time as I do it here, I vaguely
remember it to mean "don't touch".

Does anybody know that for sure?

Jeremy, please check this.

Thanks,

Volker
(This used to be commit 872d1299ebffb7b7d696013fc676820f1fa1777c)