top: bust up that overly large 'summary_show' function

top: bust up that overly large 'summary_show' function

Over the years the summary_show function has increased
from around 77 lines of code & comments to its current
size of 243 lines. This is well beyond an ideal length
of available screen rows. So this patch will split it.

We'll take the cpu and memory duties and make separate
functions out of them. Of course, this will incur some
additional call overhead but, given current cpu/memory
logic, any such increase really becomes insignificant.

Now summary_show's a svelte 57 lines of code/comments.

[ this is like what was done to that do_key function ]
[ a decade ago except overhead of new function calls ]
[ plus table lookup was even less of a concern since ]
[ a human was involved, not normal iterative output. ]

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