unix: fix SysctlUint64 on 32bit machines

TestSysctlUint64 was using vm.max_kernel_address which is only 64bit
on 64bit machines or 32bit machines with PAE. Switch to using
security.mac.labeled which is a SYSCTL_UQUAD so 64bit on all platforms.

Also:
* Correct typo in test name.

Fixes golang/go#15186

Change-Id: I88b5b6ee6a04dec0730bca1e1f0e282f3c18d20d
Reviewed-on: https://go-review.googlesource.com/36058
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed