Do not use KERN_PROC_PROC with kvm_getproc(3); instead, if only process
(and not thread) scope is to be displayed, use KERN_PROC_ALL and
accrue CPU% ourselves, as the kernel makes no attempt to do so.

Of course, this doesn't make most stats any less bogus when displaying
threaded processes, but at least the CPU time is added up and not just
always 0.00%. There are still issues with SCHED_ULE in top(1) that
cause other processes to display 0.00% CPU when they in fact have used
more.