This enables rendering of the original bootchart charts for CPU, disk
and memory usage. It depends on the /proc samples recorded by the
updated buildstats.bbclass. Currently, empty charts CPU and disk usage
charts are drawn if that data is not present; the memory chart already
gets skipped when there's no data, which will also have to be added
for the other two.
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
