top: parent total cpu includes collapsed children, pgm

Now, when a parent's children have been collapsed, the
cpu used by those unseen tasks will disappear no more.
Instead such tics will be added to the parent's total.

[ if one wished a return to the 'land of lost tics', ]
[ the '#define TREE_VCPUOFF' directive is available. ]

------------------------------------------------------
Note: With collapsible parents now displaying children
cpu usage, it will eventually be noticed the cpu stats
for the summary area and task areas often vary widely.

It's worth a reminder that for top's summary area each
individual cpu and the cpu summary is limited to 100%,
regardless of how many tics a linux kernel may export.

An individual task is limited to 100% times the number
of threads. But, in no case will cpu usage ever exceed
100% times total number of processors. Such limits are
further reduced under 'Solaris' mode ('I' toggle off).
In this mode, a task cpu usage will never exceed 100%.
These limits will now also apply to collapsed parents.

In addition to those influences, results are subjected
to kernel timer sampling anomalies and the distortions
inherent in a small sample size, made worse by smaller
delay intervals. Often there is just 1 or 2 tics for a
few tasks at smaller intervals such as: 1/10th second.

Anyway, should questions on this subject arise, a good
starting point, beyond the reminders above, is the 1st
link listed below. Those other links were derivatives.

Reference(s):
. from the kernel documentation
https://www.kernel.org/doc/Documentation/cpu-load.txt
. as mentioned in the above kernel documentation
https://lkml.org/lkml/2007/2/12/6
. from above, with many more links on the subject
https://www.boblycat.org/~malc/apc/

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

top/top.h

@@ -48,6 +48,7 @@
 //#define TERMIOS_ONLY            /* just limp along with native input only  */
 //#define TREE_NORESET            /* sort keys do NOT force forest view OFF  */
 //#define TREE_SCANALL            /* rescan array w/ forest view, avoid sort */
+//#define TREE_VCPUOFF            /* a collapsed parent excludes child's cpu */
 //#define TREE_VPROMPT            /* pid collapse/expand prompt, vs. top row */
 //#define TREE_VWINALL            /* pid collapse/expand impacts all windows */
 //#define USE_X_COLHDR            /* emphasize header vs. whole col, for 'x' */