The top program already incorporated a modest delay at
startup so that some minimal process cpu history could
be established. However, Summary Area system level cpu
statistic history reflected usage since boot. As such,
unchanging % values would be shown with every restart.

This commit just adopts the same approach used in task
%CPU history for the Summary Area statistics. In other
words, it introduces a 'priming read' at startup as is
found in the newlib implementation for the <stat> API.

Reference(s):
procps-ng/procps!42



Signed-off-by: Jim Warner <james.warner@comcast.net>