Change top's notion of idle processes / threads

[Jamie Landeg-Jones]

John, the changes are good.

The "'trickling' but still not idle" processes now show up as they should.

However, it has exposed one quirk in the display:

Sorting is done by WCPU followed by total processor time.

Processes which aren't idle (but are using so little cpu it shows as 0.00%)
show below processes which are truely idle, but have totaled more processor
time overall.

This is more noticable with your new patch, as toggling between idle-only
and full now shows processes appearing higher in the list than some which
only appear in the non-idle view!

Ideally, processes where cpu "is virtually 0.00% but really a smidgen higher"
should be display higher.

I realise the pctcpu granularity is at fault here.

Basically, what I'm saying is that truely idle processes should appear below
other processes reporting 0.00% cpu.

In other words, what I'm asking is: shouldn't the cpu sort priority not
simply be keyed on 'ki_pctcpu', but on a primary key based on
"if cur->ki_runtime == old->ki_runtime ?" followed by secondary key ki_pctcpu. 

Or even easier, shouldn't simply sorting on (cur->ki_runtime - old->ki_runtime)
suffice?

Is this a valid point, and if it is, is it practical, and/or easy enough to
achieve? I'll even have a stab at it myself tomorrow, after hopefully getting
some sleep (32 hours without sleep - sorry for incoherency - insomnia is a PITA)

Cheers,
Jamie