sysstat version 12.5.6 final packaging.
Changelog added.
spec and lsm files updated.

This version includes a complete rewriting of the code used to collect
and display interrupts statistics. These are now collected from the
/proc/interrupts file instead of the /proc/stat one, and are displayed
for each CPU.

Signed-off-by: Sebastien GODARD <[email protected]>