top: update latest CPU % distortions understanding

We originally approached the potential problem of
% CPU distortions as unique to Nehalem type cpus.
The latest information suggests that it may have
been due to a kernel anomaly that has since been
corrected.

Yet even without such a cpu, wide disparities in
tics allocation among all available cpus have
sometimes been observed -- spikes as it were in
the normal pattern.  This has happened under both
version 2.26.38-13 and 3.0.0-15 kernels.

The small amount of additional code addressing the
original problem carries very little overhead.  It
is being retained to afford protection against any
future tic accounting aberrations.

In this commit, supporting programmer comments have
been divorced from any particular cpu type.  Also,
another variable and manifest constant will now be
eliminated when CPU_ZEROTICS is defined.

References:
commit 02508b3d76
http://www.freelists.org/post/procps/CStates-handling-new-switch,50

top/top.c

@@ -1836,14 +1836,13 @@ static CPU_t *cpus_refresh (CPU_t *cpus) {
       , &cpus[Cpu_faux_tot].cur.i, &cpus[Cpu_faux_tot].cur.w, &cpus[Cpu_faux_tot].cur.x
       , &cpus[Cpu_faux_tot].cur.y, &cpus[Cpu_faux_tot].cur.z))
          error_exit(N_txt(FAIL_statget_txt));
+#ifndef CPU_ZEROTICS
    cpus[Cpu_faux_tot].cur.tot = cpus[Cpu_faux_tot].cur.u + cpus[Cpu_faux_tot].cur.s
       + cpus[Cpu_faux_tot].cur.n + cpus[Cpu_faux_tot].cur.i + cpus[Cpu_faux_tot].cur.w
       + cpus[Cpu_faux_tot].cur.x + cpus[Cpu_faux_tot].cur.y + cpus[Cpu_faux_tot].cur.z;
-#ifndef CPU_ZEROTICS
-   /* if a Nehalem type cpu has been turned off completely, and thus registers
-      very few total tics, we'll force it to be treated as idle when that total
-      falls below a % of those expected -- other cpus will register their full
-      number of expected tics as 'idle' and thus won't be effected */
+   /* if a cpu has registered substantially fewer tics than those expected,
+      we'll force it to be treated as 'idle' so as not to present misleading
+      percentages. */
    cpus[Cpu_faux_tot].edge =
       ((cpus[Cpu_faux_tot].cur.tot - cpus[Cpu_faux_tot].sav.tot) / smp_num_cpus) / (100 / TICS_EDGE);
 #endif
@@ -1866,9 +1865,9 @@ static CPU_t *cpus_refresh (CPU_t *cpus) {
       }
 #ifndef CPU_ZEROTICS
       cpus[i].edge = cpus[Cpu_faux_tot].edge;
-#endif
       // this is for symmetry only, it's not currently required
       cpus[i].cur.tot = cpus[Cpu_faux_tot].cur.tot;
+#endif
 #ifdef PRETEND4CPUS
       cpus[i].id = i;
 #endif