Add new structures for exporting the cputime statistics via 64 bit counters

Add new structures for exporting the cputime statistics via 64 bit counters
and redo the timer frequence export.
Provide the interface glue for libkinfo and libkcore.
Additionally provide interfaces to query ccpu, the number of cpus, tk_nin
and tk_nout.
Remove those fields from devstat.h's struct statinfo.
Remove kvm dependency of rpc.rstatd by using the newly added libkinfo
functions and the sysctl interface for vmmeter.
Use the new interface in systat, the iostat part is now kvm-free.
Use kinfo_get_sched_stathz in time.
Use the kinfo interface for everything beside getting the actual process list
in top. This also removes the Last PID, which could be added back easily.
Since the feature is not that useful and breaks e.g. the jail isolation,
I haven't added a sysctl to read nextpid.
Use the kinfo interface in vmstat.
Use the kinfo interface in iostat. iostat is now kvm-free and not
setgid kmem anymore. This also means that iostat can't be applied to
coredump anymore. If this functionality is important, the kcore kinfo wrapper
can be added easily.