cpu time off by a factor of 40x on M1 Macs

[andreimatei]

I believe ProcTime.Get is broken on M1 (and probably M2) Macs.
It does

	self.User = uint64(info.ptinfo.pti_total_user) / uint64(time.Millisecond)

but, on Darwin, pti_total_user needs to be scaled up by a factor of 125/3 because it is not expressed in nanos, but in "mach ticks" (I believe these ticks used to be nanos on Intel Macs). See https://developer.apple.com/documentation/driverkit/3433733-mach_timebase_info.

For reference, this is how htop does it.