Find the maximum number of the CPU, not the total number of CPUs in online
Hide CPUs in offline
Skipping missing CPU and to interrupt statistics
Print total number of CPUs in header
Rework procedures used to count processors on the machine

Rework patch from troosh: No need to duplicate code used to
count the number of processors available on the machine.
Use a flag (@highest) instead.

Signed-off-by: Sebastien GODARD <sysstat@orange.fr.fake>
Rework online/offline procedure check

Rework patch from troosh: No need to add ".present" field to stats_cpu
structure. Online CPUs can be displayed with mpstat option "-P ON".

Signed-off-by: Sebastien GODARD <sysstat@orange.fr.fake>